SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e9dafa49cc249a6f7013a9a98f4ba181c688b6659432e1e0e736e040e3893f8' 
  AND token = 'hvxmPKex0fhnMWdIiPRzzWv1uktcmqUMfbyFhG376Z8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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