Most of the sounds for the queue were really loud so I have nearly muted them all. I forget to lock in, because since the champ I wanted to play was picked by the opponents, so I spent the time trying to think of who to play against him. But if they could at least add some sort of visual effect to the lock in button to make it more obvious for us, it would be greatly appreciated.
In all honesty though I would just prefer that they didn't require you to lock in your choice. It doesn't make any sense since you can still take the entire time to pick a champion. And if you don't choose it fast enough, at least you don't get booted from the queue and have to wait the 6 minutes to get back in.