Honestly, if I was you, I would be more concerned with the GPA. But before getting into that I don’t think your salary would affect your application too much.
One reason that I have come across, through various admissions committee interviews and discussions, regarding business schools asking for the salary information is to verify whether you added any real value to the organization you were working at.
Nobody curates an MBA application that doesn’t speak highly of them. Some applicants might even write recommendations themselves, but the salary slip doesn’t lie. If you did not receive a raise on your promotions or your paycheck grew very little over a long period, an admissions committee member can deduce that you weren’t too valuable an employee to the organization.
But, don’t worry too much as it’s more of a relative evaluation. Meaning, your salary won’t necessarily be compared with an employee working in a Fortune 500 company in the same position. It will be compared with the kind of raise and paycheck other employees at your firm or similar firms receive.
But you can explain the reason for a low salary in the optional essay or additional information section.
Coming back to your GPA, schools are much stingier about GPA than any other things. They like to maintain a lower limit for GPA at 3 points. Thus, aim at the highest GMAT score possible for you.