But she couldn't find the key to open the lock.

He used a pick to open the lock of a door.

He passed the key across to me, and sat back in his chair while I opened the lock.

A key is an object used to open and close locks.

With some effort, he opened the lock and pulled the door wide.

"All right, got any good ideas about opening the lock from the outside?"

I opened the lock and let the door swing open.

If you are given a key, it will not open the lock in the conventional way.

"Open the main lock and close it after we've left the ship."

"Couldn't she have been opening the lock with a key?"