SELECT 
  cscart_products.*, 
  cscart_products.ebay_status, 
  cscart_products.ebay_template_id 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    8406, 8409, 8411, 8413, 8416, 8420, 8421, 
    8424, 8430, 8431, 8432, 8433, 8436, 
    8438, 8443, 8444
  )

Query time 0.00049

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 (8406,8409,8411,8413,8416,8420,8421,8424,8430,8431,8432,8433,8436,8438,8443,8444)"
    }
  }
}