SELECT 
  cscart_products.*, 
  cscart_products.ebay_status, 
  cscart_products.ebay_template_id 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    18749, 18750, 18751, 18752, 18753, 18754, 
    18755, 18756, 18757, 18758, 18759, 
    18760, 18761, 18762, 18763, 18764
  )

Query time 0.00041

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 (18749,18750,18751,18752,18753,18754,18755,18756,18757,18758,18759,18760,18761,18762,18763,18764)"
    }
  }
}