In X-Men: First class we see that Mystique (Raven) and Charles grow up together and at that point of time Mystique, Charles and Eric all are of same age group. But in X-Men: The last Stand, which happens in a much later time line, we see that Mystique is still a young woman. This is especially clear after she loses her mutant powers after the injection and turns into an ordinary woman. Charles and Eric are quite old at that time. Is Mystique too ageless, like Logan?
I wondered that myself when watching it, but in fact it's actually explained right in X-Men: First Class. When Hank examines Raven's cells, he tells her that the same mutation making her transformable also slows her aging process:
You got to see this. Your genes are extraordinary, you know that? Your cells age at half the rate of a normal human. When you're 40, you'll still have the leucocytes of a teenager. You have the most incredible cellular structure I've ever seen.
So she does indeed age with time, but only half as fast as the others, which explains why she still looks rather young even when she loses her powers 40 years later (though, one would assume from this point on she then ages normally, since the mutation is gone).