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 (
    2127, 2305, 1812, 2038, 2306, 2129, 2171, 
    2039, 2040, 1985, 2114, 2344, 1949, 
    2041, 2318, 1961, 2042, 1986, 2343, 
    2077, 2172, 2185, 2159, 2216, 2218, 
    2229, 2228, 2186, 2184, 1934, 2358, 
    1994, 2006, 2075, 1962, 2065, 1992, 
    2008, 1984, 1993, 1936, 2238, 2237, 
    2311, 2298, 2043, 1954, 1953, 1752, 
    1827, 1870, 1803, 1828, 1754, 1770, 
    1879, 1874, 1829, 1864, 1904, 1842, 
    1781, 1894, 2153, 1886, 1887, 2085, 
    2195, 2130, 2382, 2011, 1919, 1922, 
    1942, 1923, 1933, 1945, 1946, 2376, 
    1746
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00102

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "26.24"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "2.15"
      },
      "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": 17,
            "rows_produced_per_join": 2,
            "filtered": "4.65",
            "index_condition": "(`cscartdevel`.`cscart_products_categories`.`product_id` in (2127,2305,1812,2038,2306,2129,2171,2039,2040,1985,2114,2344,1949,2041,2318,1961,2042,1986,2343,2077,2172,2185,2159,2216,2218,2229,2228,2186,2184,1934,2358,1994,2006,2075,1962,2065,1992,2008,1984,1993,1936,2238,2237,2311,2298,2043,1954,1953,1752,1827,1870,1803,1828,1754,1770,1879,1874,1829,1864,1904,1842,1781,1894,2153,1886,1887,2085,2195,2130,2382,2011,1919,1922,1942,1923,1933,1945,1946,2376,1746))",
            "cost_info": {
              "read_cost": "11.56",
              "eval_cost": "0.22",
              "prefix_cost": "24.09",
              "data_read_per_join": "34"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        }
      ]
    }
  }
}