Last year in Team Fortress 2, there was a random occurrence that you would get a Naughty or Nice Winter crate, which you could unlock with a specific key for that. This year, I have almost a full page of mixed naughty and nice crates, and I did get all of them this year, but noticed that in the shop there was no key for those crates. Are the keys available later or is it just an ordinary key that you buy?
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.
1This applies to all crate-events. They release the crates early, and the keys afterwards. I guess they must expect people to buy more keys when they have more crates (as opposed to buying a key for one, and then forgetting about the rest of the crates they earn)– Robotnik ♦Dec 11, 2013 at 23:10
Nothing. You cannot unbox those crates anymore, as the 2013 Winter Event has already expired.
Honestly, I would trade them. Seeing as many people would want them before the keys come out, so they can get unusual hats/strange weapons, I would sell them for about a reclaimed metal each on http://www.tf2outpost.com or http://www.trade.tf. Many people love festive items, and this is time to sell your unwanted crates.