SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    18, 16, 4, 5, 23, 24, 1, 22, 25, 6, 8, 14, 
    9, 10, 19, 21
  )

Query time 0.00051

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 (18,16,4,5,23,24,1,22,25,6,8,14,9,10,19,21)"
    }
  }
}