SELECT 
  cscart_products.*, 
  cscart_products.ebay_status, 
  cscart_products.ebay_template_id 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    20717, 20718, 20719, 20720, 20721, 20722, 
    20723, 20724, 20725, 20726, 20727, 
    20728, 20729, 20730, 20731, 20732
  )

Query time 0.00027

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 (20717,20718,20719,20720,20721,20722,20723,20724,20725,20726,20727,20728,20729,20730,20731,20732)"
    }
  }
}