SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '34de1e07eb1df4395de5c06d7deab12dc918c4878088e0de46016f3be7b9f8db' 
  AND token = 'UuDypCpqHFPVHztGY6yIzAYReCR6ZDUxEpwtUdTTbSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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