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 (
    1928, 1929, 1911, 1925, 1926, 1901, 1908, 
    1923, 1922, 1921, 1909, 1920, 1919, 
    1918, 1917, 1916, 1915, 1914, 1883, 
    1913, 1912, 1910, 1903, 1902, 1905, 
    1904, 1872, 1899, 1898, 1897, 1896, 
    1873, 1895, 1894, 1893, 1891, 1659, 
    1890, 1889, 1888, 1887, 1871, 1885, 
    1886, 1884, 1869, 1882, 1881
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00170

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products_categories",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "pt"],
      "key": "pt",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 48,
      "filtered": 100,
      "index_condition": "cscart_products_categories.product_id in (1928,1929,1911,1925,1926,1901,1908,1923,1922,1921,1909,1920,1919,1918,1917,1916,1915,1914,1883,1913,1912,1910,1903,1902,1905,1904,1872,1899,1898,1897,1896,1873,1895,1894,1893,1891,1659,1890,1889,1888,1887,1871,1885,1886,1884,1869,1882,1881)"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY", "c_status", "p_category_id"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["category_id"],
      "ref": ["bacpvdev_db.cscart_products_categories.category_id"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "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')"
    }
  }
}