Sometimes you can play with the speed and “cheat” the key up or down a notch, you just have to be real careful not to overdo it and the songs have to be pretty close in key to begin with.
Sometimes the only recourse is to know your songs inside and out and which songs are in similar key. May be a bit daunting if you are not a trained musician but if yo uwork at it, it will pay off big. Back in the day when I crated my vinyl to do house music, I would crate by key, not necessarily BPM or title or genre. It’s not so important with most hiphop though as there are more beats to mix.