SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e275fad636aeef6664c1cc3807a708c44055c25fdf3d817e5d9438bb67bd701a' 
  AND token = 'kJutsnVzKTC+aeQS9iOOBu2Xilw0RPPPtShmVnUyvkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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