SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    4137, 4139, 4140, 4076, 4141, 6201, 6799
  )

Query time 0.00029

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": 7,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (4137,4139,4140,4076,4141,6201,6799)"
    }
  }
}