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 (
    55, 143, 232, 298, 337, 339, 405, 427, 
    428, 429, 430, 431, 506, 516, 517, 520, 
    521, 522, 523, 1562, 1563, 1564, 1565, 
    1566, 1567, 1568, 1569, 1570, 1755, 
    1756, 1757, 1758, 1759, 1760, 1761, 
    1762, 1763, 1764, 1765, 1766, 1767, 
    1768, 1769, 1770, 1771, 3478, 3479, 
    3480, 5477, 5556
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.01078

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": 1179,
      "filtered": 100,
      "index_condition": "cscart_products_categories.product_id in (55,143,232,298,337,339,405,427,428,429,430,431,506,516,517,520,521,522,523,1562,1563,1564,1565,1566,1567,1568,1569,1570,1755,1756,1757,1758,1759,1760,1761,1762,1763,1764,1765,1766,1767,1768,1769,1770,1771,3478,3479,3480,5477,5556)"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY", "c_status"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["category_id"],
      "ref": ["herbaria_cscart_4_18.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')"
    }
  }
}