Hi
Chinmay1998, congratulations on making a decision to apply to MBA programs! Frankly, 680 is not a low score. Moreover, your Quant score is on par (or higher) with average Quant scores at all top b-schools in the world. The overall score might be considered a bit "low" if you do not have other aspects that stand out in the application (limited international experience, no extracurricular experience, etc.)
My advice is to think holistically (and critically) about your application and, if your budget allows, to get feedback from a reputable admissions consultant. Good luck!