> It leaves open the possibility that she had a key. <
That’s how Houdini did it. When he wasn’t using trick locks he’d hide the key in his mouth.
Hiding handcuff keys is one of those things that tweekers think is cool. I guess before decriminalization there was probably a 50/50 chance they’d end up in handcuffs on any given day , so it may have been practical. But, as in this case, out of the frying pan, into the fire.