SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '536a499d63f569dc5abd12f53ca5284c39e94fe8121f576d19f8be92071b97a3' 
  AND token = 'svwUzSsU9SFn4YMoiRmCp1mZhbY4yWblq+78Co/XGlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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