If you request to see the hand , and it has not disappeared into the depths of the muck it can be shown. If the hand is shown it is generally a live hand, so you must show a better hand to claim the pot.
Saken in reply to your comment it gets unclear if a hand is live or not if the player has mucked it. There are standards for what a folded hand is that vary from casino to casino. Releasing a hand with forward motion makes a hand dead during a typical round of play, or releasing a hand over a betting line. However when special situations like the one your asking about and others come up, things get gray as to what makes a folded hand dead. Casinos always want the best hand to win so have procedures in place that allows them to bring a hand out of the muck so that the pot goes to the best hand when mistakes by players and dealers have been made.
The problem here with asking to see a hand is that dealers, floor people and players sometimes tend to think this is a live hand because it can be a known hand. They sometimes miss that the owner of the hand mucked the hand with purpose and knowledge and that it was not a mistake made by any player or dealer that the hand was folded. Technically it is not a live hand, what makes a hand dead these days is not rather or not it hits the muck but rather or not the player conceded the hand, which a player in this case has.
These days the only time a dealer can turn a hand over is when the cards have been shown to other players in the hand, otherwise a supervisor needs to be called to make decisions on rather or not the cards will be exposed, and on rather or not the player can have a claim to the pot based on these cards. 15-20 years ago players had a right to see any hand at the end of the hand. The simple procedure was if a player asked to see a hand and it was not in the muck, the dealer would tap the cards on the muck, ceremonially killing the hand, than turn the hand up for all to see. But asking to see a losing hand was considered rude and often used as a needle by players. The term "abusing the rule" starting being used when some players started asking to see most and sometimes all hands. So over time the rule evolved to what it is now. There was exception to the ceremonial killing of the hand, and that was when a winner asked to see the losers hand, the losers hand would be left live. All things considered this exception may or may not be true in your case. If the person coming over to make a decision about showing the hand believes that a winning player is asking to see a losing players hand, and that hand turns out to be better then yours, will there you go.