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 
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') 
WHERE 
  cscart_products_categories.product_id IN (
    21567, 51083, 22715, 51082, 51085, 51081, 
    51096, 51097, 51098, 51100, 51099, 
    22716, 51123, 51122, 51121, 92, 49, 
    51129, 51128, 51127, 51126, 51125, 
    48, 51176, 51174, 51173, 51172, 91, 
    51221, 137, 51224, 51223, 126, 51343, 
    51342, 51341, 51340, 47, 105, 50989, 
    31, 51366, 51367, 51368, 51369, 46, 
    51370, 51371, 51372, 51373, 51452, 
    51453, 88, 51395, 51396, 51397, 51555, 
    51556, 51496
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00195

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "165.56"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "27.43"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "ALL",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "rows_examined_per_scan": 383,
            "rows_produced_per_join": 15,
            "filtered": "4.00",
            "cost_info": {
              "read_cost": "40.09",
              "eval_cost": "1.53",
              "prefix_cost": "41.62",
              "data_read_per_join": "81K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`test_uchur_k`.`cscart_categories`.`storefront_id` in (0,1)) and ((`test_uchur_k`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`test_uchur_k`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`test_uchur_k`.`cscart_categories`.`usergroup_ids`))) and (`test_uchur_k`.`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": [
              "test_uchur_k.cscart_categories.category_id"
            ],
            "rows_examined_per_scan": 18,
            "rows_produced_per_join": 27,
            "filtered": "9.95",
            "index_condition": "(`test_uchur_k`.`cscart_products_categories`.`product_id` in (21567,51083,22715,51082,51085,51081,51096,51097,51098,51100,51099,22716,51123,51122,51121,92,49,51129,51128,51127,51126,51125,48,51176,51174,51173,51172,91,51221,137,51224,51223,126,51343,51342,51341,51340,47,105,50989,31,51366,51367,51368,51369,46,51370,51371,51372,51373,51452,51453,88,51395,51396,51397,51555,51556,51496))",
            "cost_info": {
              "read_cost": "68.94",
              "eval_cost": "2.74",
              "prefix_cost": "138.14",
              "data_read_per_join": "438"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        }
      ]
    }
  }
}