It's in the center. If you slide the screw driver along the outside edge of the seats until you hit the lock, then pull it back just a little bit maintaining pressure against the lock, you'll find the front of it. There's a small tab there. Push in on it and it will unlock.
It may help to pull up on the seat a bit as you do this.
the button is on the front side of the latch, i have always used the male connector of the seat belt to push it in with, no sharp edges to damage anything with, and is almost the same size as the button.