SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0a3c96a18cb785234c0dc15529719af6c8d98fec9a9fe43a67e073c9406babec' 
  AND token = 'tJ5N9DIfsTLaoyVNZ6BkU4wfheRetaMvaV7AaCVgP6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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