It all depends on what you're aiming at with your title.
The title may not be meaningful. Take Nana by Émile Zola or Old Father Goriot by Honoré de Balzac. It's merely the name of the protagonist or just a significant character. It tells nothing about the content, the story, and is too generic to indicate anything about what kind of story it is. Such a title requires a rather reputable author to sell well though.
The title may be just as short but augmented with a subtitle. The full title of Sir Thaddeus by Adam Mickiewicz is Sir Thaddeus, or the Last Lithuanian Foray: A Nobleman's Tale from the Years of 1811 and 1812 in Twelve Books of Verse. That is sure to tell more about the content.
Or the title may be mysterious, hinting at the content - like in your example. "Harry Potter and the Philosopher's Stone" - you get a bit of clue it will be about magical themes, and it has a bit of "book for youngsters" ring to it.
There's of course a whole range of other titles, more revealing, completely mysterious by being written in a strange language (even made-up language), or ones outright misguiding. Nevertheless, your fares well mid-way the range, and is actually a rather common (that doesn't mean bad!) approach.
Also, if you want to keep "The End of the World" you can use it as the subtitle, an optional extra. It won't make the title too long but it will add a little for those who hesitate a second before picking it (and you're right, it's too generic - but then nowadays apocalyptic/postapocalyptic stories sell like hot cakes, so it would surely attract audience.)