We keep our valuables under lock and key.

我们把贵重物品锁起来收好了。

《牛津词典》

He kept that book under lock and key.

他把那本书锁起来。

youdao

In the meantime, the comic book remains under lock and key with the Halland police.

在这期间，唐老鸭漫画书仍由哈兰警方妥善保管。

youdao

Walking through, it is easy to forget that women spent their entire lives here under lock and key.

BBC: Uncover the secrets of Topkapi Palace

The former partners tried to keep Cawley's new claims under lock and key at the courthouse.

FORBES: Magazine Article

In its quarterly Inflation Report it signalled that the door remains under lock and key.

ECONOMIST: The Bank is in no hurry to raise the price of money