Item description:

Figured this out a few mintues ago after seeing someone on youtube bragging about having unlimited keys.

It is best to have two controllers for this (You get a new key on every account you make, but this is useful)

With the first controller sign in to your “main” account.
WIth the second controller open the guide and create a new offline profile.
Press start on the first controller and join the game with your new offline profile (Enabling split-screen)
You will see a message appear saying that you have a golden key available
Go to the chest with your offline profile and open it, take the contents with your “main” profile.
Sign out of the offline profile, create another offline profile, join the game, get another key.
Repeat.
There are ways to open the chest with your “main” account even if the guest is the one with the key, I haven’t figured out how though.

Feel free to try out some new things and post the results, maybe making new characters with the offline account? Let me know if you find something that works better.

The higher the level the better the loot, I recommend using a level 50 modded save for your offline profiles to get the best loot.