SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '13a9a2b98593a3665c459d155e90ec6700c74bc449d4f123b5eac4eed02efd3d' 
  AND token = 'mkWfj/Qs55aCsDnrXKuhGAbYXjSZOouvCwxFygn8n/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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