Mara, Shane's wife (at least I think that's what her name is), used the key to the locker before to get that money to her mother and after that, they moved it and Shane never told her where, but Shane still had a year lease on the locker so he kept the key anyways even though they moved the money elsewhere. Giving Aceveda the key just showed they had nothing to hide in regards to that locker. Smart move on their part. Interesting how the cops are always one step behind and the Armenians seem to be one step ahead at this point, especially with what happened after this episode.