Well 45% is a less percentage to begin with. But however as you say your from the sc category you might get a chance or a call from a good college. Don't loose hope apply to all the good colleges. And in the end who knows you might get one.

There is no any category reservation in XAT Entrance Exam. Based on this score you can have the chance Bengal Institute of Business Studies, Kolkata, Taxila Business School, Jaipur, School of Management Sciences, Varanasi, Kejriwal Institute of Management and Development Studies, Ranchi etc. You can check your other possibilities with XAT Pathfinder Tool.

https://bschool.careers360.com/pathfinder/xat

Good Luck!