SELECT 
  cscart_products.*, 
  cscart_products.ebay_status, 
  cscart_products.ebay_template_id 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    20045, 20046, 20047, 20048, 20049, 20050, 
    20051, 20052, 20053, 20054, 20055, 
    20056, 20057, 20058, 20059, 20060
  )

Query time 0.00033

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 (20045,20046,20047,20048,20049,20050,20051,20052,20053,20054,20055,20056,20057,20058,20059,20060)"
    }
  }
}