SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    4116, 4136, 4115, 4127, 4087, 4126, 4086, 
    4128, 4089, 4091, 4108, 4085, 4090, 
    4971
  )

Query time 0.00031

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": 14,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (4116,4136,4115,4127,4087,4126,4086,4128,4089,4091,4108,4085,4090,4971)"
    }
  }
}