SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f7f38186765974137fdad8a1cd79d176eec10809a716190987e6c23092016bf' 
  AND token = '8rdVUyPOLwQt1ml+t/DM3EpDjGb/IicXdCFIO4qI/ts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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