If Sylas had to guess, the Creation of Key was probably a repairing mechanism of some sort.
Since the tower was so much like a clock, using the clock analogy would actually work pretty well here. The tower was like a watch that needed to be wound up to maintain consistent and controlled power. And the key was exactly that sort of special interlocking mechanism that could get the gears in the clock going again.
You would insert the key, wind it up, add potential energy to the spring mechanisms inside, and then everything would start running again.
Unfortunately, that was where the analogy fell flat, because obviously this was no simple clock.
If it was just normal maintenance, then yes, the Creation of Key would be fine. But handing over the Key like this when the tower was in this state would be like giving a homeless man a burger and then expecting to claw it back.
The tower didn't need a simple tune up. What it needed was the reference that the Creation of Key provided.
