SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    339, 376, 1565, 1566, 1567, 1568, 1569, 
    1570, 1612, 1613, 1614, 1615, 1616, 
    1617, 1618, 5476, 5556, 1581, 1582, 
    1583, 1584, 1585, 349, 1586, 1587
  )

Query time 0.00068

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 25,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (339,376,1565,1566,1567,1568,1569,1570,1612,1613,1614,1615,1616,1617,1618,5476,5556,1581,1582,1583,1584,1585,349,1586,1587)"
    }
  }
}