SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    1672, 1691, 1709, 2390, 1661, 1705, 1860, 
    2169, 1699, 1708, 851, 1710
  )

Query time 0.00078

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": 12,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (1672,1691,1709,2390,1661,1705,1860,2169,1699,1708,851,1710)"
    }
  }
}