It is true that your percentage are quite low for top ranked b-schools, since expectation are 70 and above, however you can still have chances, since usually it depends on your overall profile and ability to perform well during the interview if there is such. In your case you would need to score really well in GMAT, if you can get around 700 you would still have chances. However even with the lower score you may give it a try as you never know how well the other details of you may look like. Unfortunately, if you score 600 only, that would be hard to make to the school. You should also check on the exact university and its programme requirement: would they accept CAT since b-schools usually prefer GMAT or GRE, so you do not take the wrong one. Also, relax and try to write a good motivation letter and perform very well during the interview. There is always a chance if you are striving for your goal.
Wishing you all the best,