I have just recently figure out how to STILL get unlimited keys in Borderlands 2 after the patch they did a month or so back.
This unfortunately for xbox360 and ps3 users only works for PC.
Here is what you do!
First go to – C:\Users\%yourusername%\Documents\My Games\Borderlands 2\WillowGame\SaveData\RANDOMNUMBERS
You should see a Save0001 (each save for each character, so you may have Save0002/0003/etc) and a profile file. The PROFILE file is the one we will be replacing with the glitched profile which has the 254 keys in it.
Now MAKE SURE TO BACK UP YOUR SAVE AND PROFILE FILE BEFORE WE DO THIS – YOU CAN PUT IT ANYWHERE JUST REMEMBER WHERE IT IS!
Once you have made a backup of your profile file, download my golden key version of the profile file, and replace your current one in the folder listed.
You can now start borderlands, open the chest to your hearts desire, and once you are done save and exit and close Borderlands 2.
You can now replace the golden key profile with your original profile file, and start the game again. You now have all the guns you acquired and your settings/Bad Ass points back.
You can repeat this as much as you want whenever you want to open the chest!
*Download Golden Key Profile.bin file here*