[2019] Bank Vault

I have this tiny problem. On my first run through on the "Bank Vault," I picked up that secret key that allowed me into that vault area where the Hyena's stash is (Not to mention the blueprints to the Chatterbox) and I did not have a Hyena Key at the time. Now I go back in and I cannot access that secrete key any longer. So, am I s...t out of luck getting the Chatterbox Blueprint??

Thank You.