SELECT 
  cscart_products.*, 
  cscart_products.ebay_status, 
  cscart_products.ebay_template_id 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    18589, 18590, 18591, 18592, 18593, 18594, 
    18595, 18596, 18597, 18598, 18599, 
    18600, 18601, 18602, 18603, 18604
  )

Query time 0.00042

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 (18589,18590,18591,18592,18593,18594,18595,18596,18597,18598,18599,18600,18601,18602,18603,18604)"
    }
  }
}