SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2c6f80dd27a9bc4d611391e13568477caa45beddfa0f2a705318be69e2cb3299' 
  AND token = '+wQj2hhmXL4sBQFvhyRopseTVf9IwSjtkW9LniGouvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}