How can I unlock the door?

Hint 1 of 9:

You will need some help from Lockjaw here.

Hint 2 of 9:

First, where is the key to the door?

Hint 3 of 9:

Lockjaw's paws can't unlock the door.

Hint 4 of 9:

But they could put the key where Pepper can get it.

Hint 5 of 9:

Push the key underneath the door.