What to do with the Naughty and Nice Winter Crates?
Solution 1:
The keys probably are not on sale yet.
You will have to wait a little bit until they are on the Team Fortress 2 item store. It will probably appear as "New items" in the store tab when you Launch Team Fortress and then you can buy them for $2.50 each.
Solution 2:
Nothing. You cannot unbox those crates anymore, as the 2013 Winter Event has already expired.