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 (
    1557, 1556, 1555, 1554, 1553, 1551, 1549, 
    1546, 1545, 1544, 1543, 1542, 1541, 
    1540, 1539, 1538, 1537, 1512, 1534, 
    1533, 1515, 1532, 1531, 1530, 1529, 
    1528, 1527, 1526, 1508, 1525, 1524, 
    1509, 1523, 1522, 1521, 1520, 1519, 
    1518, 1517, 1516, 1277, 1494, 1507, 
    1499, 1505, 1504, 1503, 1502
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00167

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 (1557,1556,1555,1554,1553,1551,1549,1546,1545,1544,1543,1542,1541,1540,1539,1538,1537,1512,1534,1533,1515,1532,1531,1530,1529,1528,1527,1526,1508,1525,1524,1509,1523,1522,1521,1520,1519,1518,1517,1516,1277,1494,1507,1499,1505,1504,1503,1502)"
    },
    "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')"
    }
  }
}