It doesn't need to have five sharps. To get comfortable with the piano, play anything that you know well.
If you're really worried that the piano might have a defect, such as a unison out of tune or a damper that doesn't do it's job, you need to play a slowish chromatic scale through the whole range. If it turns out that there is a serious problem with the instrument just before the concert, you wont be the only one affected and emergency measures are called for: is there a piano tuner in the house, is there another piano...
But that shouldn't be the case. To get a feel for the piano, you don't need to play all the keys that are used in your piece. Just pick something you know and love, and play as much of it as you have time for.