SELECT 
  cscart_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      cscart_products_categories.link_type = "M", 
      CONCAT(
        cscart_products_categories.category_id, 
        "M"
      ), 
      cscart_products_categories.category_id
    )
  ) AS category_ids, 
  product_position_source.position AS position 
FROM 
  cscart_products_categories 
  INNER JOIN cscart_categories ON cscart_categories.category_id = cscart_products_categories.category_id 
  AND cscart_categories.storefront_id IN (0, 1) 
  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') 
  LEFT JOIN cscart_products_categories AS product_position_source ON cscart_products_categories.product_id = product_position_source.product_id 
  AND product_position_source.category_id = 166 
WHERE 
  cscart_products_categories.product_id IN (
    154, 53, 52, 161, 165, 166, 86, 106, 105, 
    101, 33, 32, 163, 155, 55, 69, 184, 183, 
    133, 132, 125, 120, 146, 147, 145, 117, 
    113, 157, 68, 29, 6, 8, 14, 9, 10, 19, 21, 
    50, 51, 49, 48, 54, 153, 164, 248, 65, 
    64, 63
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00109

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "39.46"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "1.73"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "ALL",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "rows_examined_per_scan": 98,
            "rows_produced_per_join": 3,
            "filtered": "4.00",
            "cost_info": {
              "read_cost": "22.48",
              "eval_cost": "0.78",
              "prefix_cost": "23.26",
              "data_read_per_join": "13K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`danishecarter_25_march`.`cscart_categories`.`storefront_id` in (0,1)) and ((`danishecarter_25_march`.`cscart_categories`.`usergroup_ids` = '') or find_in_set(0,`danishecarter_25_march`.`cscart_categories`.`usergroup_ids`) or find_in_set(1,`danishecarter_25_march`.`cscart_categories`.`usergroup_ids`)) and (`danishecarter_25_march`.`cscart_categories`.`status` in ('A','H')))"
          }
        },
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "danishecarter_25_march.cscart_categories.category_id"
            ],
            "rows_examined_per_scan": 2,
            "rows_produced_per_join": 1,
            "filtered": "22.10",
            "index_condition": "(`danishecarter_25_march`.`cscart_products_categories`.`product_id` in (154,53,52,161,165,166,86,106,105,101,33,32,163,155,55,69,184,183,133,132,125,120,146,147,145,117,113,157,68,29,6,8,14,9,10,19,21,50,51,49,48,54,153,164,248,65,64,63))",
            "cost_info": {
              "read_cost": "10.82",
              "eval_cost": "0.35",
              "prefix_cost": "35.65",
              "data_read_per_join": "27"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "table": {
            "table_name": "product_position_source",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id",
              "product_id"
            ],
            "key_length": "6",
            "ref": [
              "const",
              "danishecarter_25_march.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 1,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "1.73",
              "eval_cost": "0.35",
              "prefix_cost": "37.73",
              "data_read_per_join": "27"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}