SELECT 
  SQL_CALC_FOUND_ROWS products.product_id, 
  descr1.product as product, 
  companies.company as company_name, 
  popularity.total as popularity, 
  MIN(
    IF(
      prices.percentage_discount = 0, 
      prices.price, 
      prices.price - (
        prices.price * prices.percentage_discount
      )/ 100
    )
  ) as price, 
  absolute_rating.rating AS absolute_vendor_rating, 
  products.product_type, 
  products.parent_product_id, 
  products.list_price as list_price, 
  MAX(
    100 - (
      (prices.price * 100) / products.list_price
    )
  ) AS sales_discount 
FROM 
  cscart_products as products 
  LEFT JOIN cscart_product_features_values ON cscart_product_features_values.product_id = products.product_id 
  AND cscart_product_features_values.lang_code = 'de' 
  LEFT JOIN cscart_product_features ON cscart_product_features_values.feature_id = cscart_product_features.feature_id 
  LEFT JOIN cscart_product_descriptions as descr1 ON descr1.product_id = products.product_id 
  AND descr1.lang_code = 'de' 
  LEFT JOIN cscart_product_prices as prices ON prices.product_id = products.product_id 
  AND prices.lower_limit = 1 
  LEFT JOIN cscart_product_prices as prices_2 ON prices.product_id = prices_2.product_id 
  AND prices_2.lower_limit = 1 
  AND prices_2.price < prices.price 
  AND prices_2.usergroup_id IN (0, 0, 1) 
  LEFT JOIN cscart_companies AS companies ON companies.company_id = products.company_id 
  INNER JOIN cscart_products_categories as products_categories ON products_categories.product_id = products.product_id 
  INNER JOIN cscart_categories ON cscart_categories.category_id = products_categories.category_id 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  AND cscart_categories.storefront_id IN (0, 1) 
  LEFT JOIN cscart_product_popularity as popularity ON popularity.product_id = products.product_id 
  LEFT JOIN cscart_absolute_rating AS absolute_rating ON absolute_rating.object_id = products.company_id 
  AND absolute_rating.object_type = 'company' 
  LEFT JOIN cscart_product_sales ON cscart_product_sales.product_id = products.product_id 
  AND cscart_product_sales.category_id = products_categories.category_id 
WHERE 
  1 
  AND companies.status IN ('A') 
  AND (
    products.usergroup_ids = '' 
    OR FIND_IN_SET(0, products.usergroup_ids) 
    OR FIND_IN_SET(1, products.usergroup_ids)
  ) 
  AND products.status IN ('A') 
  AND prices.usergroup_id IN (0, 0, 1) 
  AND prices_2.price IS NULL 
  AND products.parent_product_id = 0 
  AND products.product_type != 'D' 
GROUP BY 
  products.product_id 
HAVING 
  sales_discount > 0 
  AND price < list_price 
ORDER BY 
  sales_discount desc, 
  products.product_id ASC 
LIMIT 
  0, 8

Query time 0.02440

JSON explain

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    "cost_info": {
      "query_cost": "78.19"
    },
    "ordering_operation": {
      "using_filesort": true,
      "grouping_operation": {
        "using_temporary_table": true,
        "using_filesort": false,
        "nested_loop": [
          {
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              "access_type": "system",
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              "used_columns": [
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                "rating"
              ]
            }
          },
          {
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              "table_name": "companies",
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              "possible_keys": [
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              ],
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              "rows_produced_per_join": 1,
              "filtered": "25.00",
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              },
              "used_columns": [
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              ],
              "attached_condition": "(`danishecarter_latest`.`companies`.`status` = 'A')"
            }
          },
          {
            "table": {
              "table_name": "cscart_categories",
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            }
          },
          {
            "table": {
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              "access_type": "ref",
              "possible_keys": [
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                "pt"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
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              ],
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              "used_columns": [
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          {
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              "access_type": "eq_ref",
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              ],
              "key": "PRIMARY",
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              "filtered": "8.83",
              "cost_info": {
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                "eval_cost": "0.21",
                "prefix_cost": "35.19",
                "data_read_per_join": "4K"
              },
              "used_columns": [
                "product_id",
                "product_type",
                "status",
                "company_id",
                "list_price",
                "usergroup_ids",
                "parent_product_id"
              ],
              "attached_condition": "((`danishecarter_latest`.`products`.`company_id` = `danishecarter_latest`.`companies`.`company_id`) and (`danishecarter_latest`.`products`.`parent_product_id` = 0) and ((`danishecarter_latest`.`products`.`usergroup_ids` = '') or find_in_set(0,`danishecarter_latest`.`products`.`usergroup_ids`) or find_in_set(1,`danishecarter_latest`.`products`.`usergroup_ids`)) and (`danishecarter_latest`.`products`.`status` = 'A') and (`danishecarter_latest`.`products`.`product_type` <> 'D'))"
            }
          },
          {
            "table": {
              "table_name": "popularity",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY",
                "total"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "product_id"
              ],
              "key_length": "3",
              "ref": [
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              ],
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              "used_columns": [
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              ]
            }
          },
          {
            "table": {
              "table_name": "cscart_product_sales",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY",
                "pa"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
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                "product_id"
              ],
              "key_length": "6",
              "ref": [
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              ],
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              },
              "used_columns": [
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              ]
            }
          },
          {
            "table": {
              "table_name": "prices",
              "access_type": "ref",
              "possible_keys": [
                "usergroup",
                "product_id",
                "lower_limit",
                "usergroup_id"
              ],
              "key": "usergroup",
              "used_key_parts": [
                "product_id"
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              "key_length": "3",
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              ],
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              "filtered": "98.10",
              "index_condition": "((`danishecarter_latest`.`prices`.`lower_limit` = 1) and (`danishecarter_latest`.`prices`.`usergroup_id` in (0,0,1)))",
              "cost_info": {
                "read_cost": "3.82",
                "eval_cost": "0.61",
                "prefix_cost": "40.05",
                "data_read_per_join": "73"
              },
              "used_columns": [
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                "price",
                "percentage_discount",
                "lower_limit",
                "usergroup_id"
              ]
            }
          },
          {
            "table": {
              "table_name": "prices_2",
              "access_type": "ref",
              "possible_keys": [
                "usergroup",
                "product_id",
                "lower_limit",
                "usergroup_id"
              ],
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                "product_id"
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              "not_exists": true,
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              },
              "used_columns": [
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                "price",
                "lower_limit",
                "usergroup_id"
              ],
              "attached_condition": "(<if>(found_match(prices_2), isnull(`danishecarter_latest`.`prices_2`.`price`), true) and <if>(is_not_null_compl(prices_2), ((`danishecarter_latest`.`prices_2`.`lower_limit` = 1) and (`danishecarter_latest`.`prices_2`.`price` < `danishecarter_latest`.`prices`.`price`) and (`danishecarter_latest`.`prices_2`.`usergroup_id` in (0,0,1))), true))"
            }
          },
          {
            "table": {
              "table_name": "cscart_product_features_values",
              "access_type": "ref",
              "possible_keys": [
                "lang_code",
                "product_id",
                "idx_product_feature_variant_id"
              ],
              "key": "idx_product_feature_variant_id",
              "used_key_parts": [
                "product_id"
              ],
              "key_length": "3",
              "ref": [
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              ],
              "rows_examined_per_scan": 42,
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              "filtered": "100.00",
              "using_index": true,
              "cost_info": {
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                "prefix_cost": "63.09",
                "data_read_per_join": "29K"
              },
              "used_columns": [
                "feature_id",
                "product_id",
                "lang_code"
              ],
              "attached_condition": "<if>(is_not_null_compl(cscart_product_features_values), (`danishecarter_latest`.`cscart_product_features_values`.`lang_code` = 'de'), true)"
            }
          },
          {
            "table": {
              "table_name": "cscart_product_features",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
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              ],
              "key_length": "3",
              "ref": [
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              },
              "used_columns": [
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              ]
            }
          },
          {
            "table": {
              "table_name": "descr1",
              "access_type": "eq_ref",
              "possible_keys": [
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                "product_id"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
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              ],
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              },
              "used_columns": [
                "product_id",
                "lang_code",
                "product"
              ]
            }
          }
        ]
      }
    }
  }
}