The commercial boys selling throttle locks opportunistically (correct English, or too literally translated ?) call it a "cruise control", which it isn't : it's "just" a throttle lock, locking the throttle in a certain position, meaning that position itself is fixed, not your speed. Which doesn't mean it can't be useful, e.g. on longer highway routes towards a far-away holiday destination, to release the pressure on your right shoulder and right hand, albeit for a couple of seconds every now and then...
I hate this commercial selling terminology, kind of like selling exhaust fumes for fresh air.