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 (
    1987, 2110, 2111, 2112, 1900, 1813, 1820, 
    2366, 1897, 1750, 1924, 2227, 2204, 
    2010, 2309, 2060, 2122, 2274, 2061, 
    1918, 1913, 1958, 2290, 1751, 1957, 
    2202, 1814, 2331, 1748, 2005, 2214, 
    2342, 2215, 2211, 2225, 2212, 2213, 
    2226, 2151, 1882, 1815, 1853, 1759, 
    2001, 2276, 2231, 2281, 2379, 2388, 
    2115, 1929, 2373, 2372, 2374, 1760, 
    1807, 1847, 2363, 1816, 2146, 2201, 
    2386, 2359, 2279, 1843, 1859, 1794, 
    1793, 1817, 1795, 2278, 1818, 1784, 
    1819, 1849, 2338, 2383, 2337, 2336, 
    2389
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00102

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "25.34"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "2.20"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "ALL",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "rows_examined_per_scan": 68,
            "rows_produced_per_join": 2,
            "filtered": "4.00",
            "cost_info": {
              "read_cost": "7.63",
              "eval_cost": "0.27",
              "prefix_cost": "7.91",
              "data_read_per_join": "9K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`cscartdevel`.`cscart_categories`.`storefront_id` in (0,1)) and ((`cscartdevel`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`cscartdevel`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`cscartdevel`.`cscart_categories`.`usergroup_ids`))) and (`cscartdevel`.`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": [
              "cscartdevel.cscart_categories.category_id"
            ],
            "rows_examined_per_scan": 16,
            "rows_produced_per_join": 2,
            "filtered": "5.05",
            "index_condition": "(`cscartdevel`.`cscart_products_categories`.`product_id` in (1987,2110,2111,2112,1900,1813,1820,2366,1897,1750,1924,2227,2204,2010,2309,2060,2122,2274,2061,1918,1913,1958,2290,1751,1957,2202,1814,2331,1748,2005,2214,2342,2215,2211,2225,2212,2213,2226,2151,1882,1815,1853,1759,2001,2276,2231,2281,2379,2388,2115,1929,2373,2372,2374,1760,1807,1847,2363,1816,2146,2201,2386,2359,2279,1843,1859,1794,1793,1817,1795,2278,1818,1784,1819,1849,2338,2383,2337,2336,2389))",
            "cost_info": {
              "read_cost": "10.88",
              "eval_cost": "0.22",
              "prefix_cost": "23.14",
              "data_read_per_join": "35"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        }
      ]
    }
  }
}