SELECT 
  cscart_product_feature_variant_descriptions.variant, 
  cscart_product_feature_variants.variant_id, 
  cscart_product_feature_variants.feature_id, 
  cscart_product_features_values.variant_id as selected, 
  cscart_product_features.feature_type, 
  cscart_seo_names.name as seo_name, 
  cscart_seo_names.path as seo_path, 
  cscart_product_feature_variants.mdc_variant 
FROM 
  cscart_product_feature_variants 
  LEFT JOIN cscart_product_feature_variant_descriptions ON cscart_product_feature_variant_descriptions.variant_id = cscart_product_feature_variants.variant_id 
  AND cscart_product_feature_variant_descriptions.lang_code = 'de' 
  INNER JOIN cscart_product_features_values ON cscart_product_features_values.variant_id = cscart_product_feature_variants.variant_id 
  AND cscart_product_features_values.lang_code = 'de' 
  AND cscart_product_features_values.product_id = 686 
  AND cscart_product_features_values.feature_id = cscart_product_feature_variants.feature_id 
  LEFT JOIN cscart_product_features ON cscart_product_features.feature_id = cscart_product_feature_variants.feature_id 
  LEFT JOIN cscart_seo_names ON cscart_seo_names.object_id = cscart_product_feature_variants.variant_id 
  AND cscart_seo_names.type = 'e' 
  AND cscart_seo_names.dispatch = '' 
  AND cscart_seo_names.lang_code = 'en' 
WHERE 
  1 
  AND cscart_product_feature_variants.feature_id IN (
    1042, 1022, 1036, 1061, 1033, 1053, 1028, 
    1052, 1056, 1062, 1063, 1023, 1044, 
    1048, 1068, 1029, 1030, 1051, 1031
  ) 
GROUP BY 
  cscart_product_feature_variants.variant_id 
ORDER BY 
  cscart_product_feature_variants.position, 
  cscart_product_feature_variant_descriptions.variant

Query time 0.00607

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "194.87"
    },
    "ordering_operation": {
      "using_filesort": true,
      "grouping_operation": {
        "using_temporary_table": true,
        "using_filesort": false,
        "nested_loop": [
          {
            "table": {
              "table_name": "cscart_product_features_values",
              "access_type": "range",
              "possible_keys": [
                "PRIMARY",
                "fl",
                "variant_id",
                "lang_code",
                "product_id",
                "fpl",
                "idx_product_feature_variant_id"
              ],
              "key": "idx_product_feature_variant_id",
              "used_key_parts": [
                "product_id",
                "feature_id",
                "lang_code"
              ],
              "key_length": "12",
              "rows_examined_per_scan": 22,
              "rows_produced_per_join": 22,
              "filtered": "100.00",
              "using_index": true,
              "cost_info": {
                "read_cost": "6.25",
                "eval_cost": "4.40",
                "prefix_cost": "10.65",
                "data_read_per_join": "17K"
              },
              "used_columns": [
                "feature_id",
                "product_id",
                "variant_id",
                "lang_code"
              ],
              "attached_condition": "((`danishecarter_latest`.`cscart_product_features_values`.`product_id` = 686) and (`danishecarter_latest`.`cscart_product_features_values`.`feature_id` in (1042,1022,1036,1061,1033,1053,1028,1052,1056,1062,1063,1023,1044,1048,1068,1029,1030,1051,1031)) and (`danishecarter_latest`.`cscart_product_features_values`.`lang_code` = 'de'))"
            }
          },
          {
            "table": {
              "table_name": "cscart_product_feature_variants",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY",
                "feature_id"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "variant_id"
              ],
              "key_length": "3",
              "ref": [
                "danishecarter_latest.cscart_product_features_values.variant_id"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 18,
              "filtered": "83.34",
              "cost_info": {
                "read_cost": "22.00",
                "eval_cost": "3.67",
                "prefix_cost": "37.05",
                "data_read_per_join": "48K"
              },
              "used_columns": [
                "variant_id",
                "feature_id",
                "position",
                "mdc_variant"
              ],
              "attached_condition": "(`danishecarter_latest`.`cscart_product_feature_variants`.`feature_id` = `danishecarter_latest`.`cscart_product_features_values`.`feature_id`)"
            }
          },
          {
            "table": {
              "table_name": "cscart_product_features",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "feature_id"
              ],
              "key_length": "3",
              "ref": [
                "danishecarter_latest.cscart_product_features_values.feature_id"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 18,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "18.34",
                "eval_cost": "3.67",
                "prefix_cost": "59.05",
                "data_read_per_join": "21K"
              },
              "used_columns": [
                "feature_id",
                "feature_type"
              ]
            }
          },
          {
            "table": {
              "table_name": "cscart_product_feature_variant_descriptions",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "variant_id",
                "lang_code"
              ],
              "key_length": "9",
              "ref": [
                "danishecarter_latest.cscart_product_features_values.variant_id",
                "const"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 18,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "18.34",
                "eval_cost": "3.67",
                "prefix_cost": "81.06",
                "data_read_per_join": "55K"
              },
              "used_columns": [
                "variant_id",
                "variant",
                "lang_code"
              ]
            }
          },
          {
            "table": {
              "table_name": "cscart_seo_names",
              "access_type": "ref",
              "possible_keys": [
                "PRIMARY",
                "dispatch"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "object_id",
                "type",
                "dispatch",
                "lang_code"
              ],
              "key_length": "206",
              "ref": [
                "danishecarter_latest.cscart_product_features_values.variant_id",
                "const",
                "const",
                "const"
              ],
              "rows_examined_per_scan": 5,
              "rows_produced_per_join": 91,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "95.48",
                "eval_cost": "18.34",
                "prefix_cost": "194.87",
                "data_read_per_join": "155K"
              },
              "used_columns": [
                "name",
                "object_id",
                "type",
                "dispatch",
                "path",
                "lang_code"
              ]
            }
          }
        ]
      }
    }
  }
}

Result

variant variant_id feature_id selected feature_type seo_name seo_path mdc_variant
1 (None) 18936 1028 18936 S EMISSIONSSTICKER_NONE
16 23427 1029 23427 N 16
2 22744 1048 22744 N 2
479 23428 1061 23428 N 479
AIXAM 21731 1023 21731 E aixam AIXAM
Automatic 22768 1051 22768 S AUTOMATIC_GEAR
Black 22827 1062 22827 S BLACK
Camera 22869 1068 22869 M REAR_VIEW_CAM
carplay 23420 1042 23420 M carplay
centralLocking 23269 1042 23269 M centralLocking
City 19375 1044 19375 S City
Cloth 22836 1063 22836 S FABRIC
electricWindows 23267 1042 23267 M electricWindows
EU Edition 19015 1036 19015 S EU
Fixed 18937 1030 18937 S FIXED
Front wheel drive 22782 1053 22782 S FRONT
handsFreePhoneSystem 23422 1042 23422 M handsFreePhoneSystem
Hybrid (petrol/electric) 22801 1056 22801 S HYBRID
New vehicle 18941 1031 18941 S NEW
No 18943 1033 18943 S N
Saloon 21675 1022 21675 S Limousine
Silver 22780 1052 22780 S SILVER
warranty 23270 1042 23270 M warranty