There isn't one (for 5th edition), to the best of my knowledge.
Still, superhuman strength is attainable by numerous means, so it's a fair question. Due to the lack of leverage, I'd perhaps be inclined to say it simply can't be done, but that's a very unfun answer.
I'd default to the front of the book for a task like this that doesn't have its own rule. Pg 45 establishes thresholds for various tests. If I were to allow it at all, I'd call busting out of restraints at minimum Very Hard, and probably Extreme for the metal/reinforced cuffs. Maybe a lower threshold to rip a handcuff open with your bare hands if you had leverage, but without leverage I'd say Very Hard at minimum.
Feats of Strength isn't governed by a skill, so it'd be Attribute + Attribute. STR is clearly called for; STR + BOD is probably what I'd call it. Perhaps STR + WIL, representing the ability to force your wrists to go through the pain...