Instead of unlocking only when you want to use the bank or trade, etc, why not unlock first by clicking on the lock before you start doing anything else in game? When you unlock by clicking directly on the lock (see red arrow below), the Use Lock box will pop up. You don't have to tick the Open Lock box at all using this method; you just input the Lock Code straight away.
When you do this, your lock code is open the entirety of your game and you don't need to go through having to unlock all the time and ticking the box.
If you don't do this, every time you want to open bank, warehouse, do trade, drop items, or NPC items, you will have to use the tick box to open the lock.
This can get quite tedious.