Keep the items you want and toss the ones you don't on the floor.
Once that is done then you can open the chest at your liesure. The trick is to just empty all of your items into the vault giving you the maximum slots before using the profile.bin. That means any new weapons you find in the chest must stay on your character each time you save and quit because they will just dissapear if placed in the vault or stash. But if you copy the file to a new folder within the save directory and just copy and past the file each time you use the keys, you can indeffinately use the file to repeat opening the chest 'twenty times' over and over.
The whole idea is that if you have say twenty keys, the profile.bin file wil have that amount and will overwrite your amount each time you open the chest. The 'save0001' file stores items that are physically carried by the character. The profile.bin file stores all data regarding external storage and items outside of the character's inventory like the vault, claptrap's stash, and golden keys.
