SELECT 
  cscart_products.*, 
  cscart_products.ebay_status, 
  cscart_products.ebay_template_id 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    19965, 19966, 19967, 19968, 19969, 19970, 
    19971, 19972, 19973, 19974, 19975, 
    19976, 19977, 19978, 19979, 19980
  )

Query time 0.00032

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 (19965,19966,19967,19968,19969,19970,19971,19972,19973,19974,19975,19976,19977,19978,19979,19980)"
    }
  }
}