SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    5610, 526, 3544, 530, 527, 528, 543, 544, 
    537, 529, 540, 539, 533, 536, 531, 535
  )

Query time 0.00040

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": 16,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (5610,526,3544,530,527,528,543,544,537,529,540,539,533,536,531,535)"
    }
  }
}