SELECT 
  cscart_products.*, 
  cscart_products.ebay_status, 
  cscart_products.ebay_template_id 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    19981, 19982, 19983, 19984, 19985, 19986, 
    19987, 19988, 19989, 19990, 19991, 
    19992, 19993, 19994, 19995, 19996
  )

Query time 0.00043

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 (19981,19982,19983,19984,19985,19986,19987,19988,19989,19990,19991,19992,19993,19994,19995,19996)"
    }
  }
}