It is practically impossible for any employee to ask for salary hike since it may backfire if your boss says no. Will look terribly awkward from next day onwards to work with him. Relationship may spoil.
The best option for asking salary hike is first to find a new opportunity and get the offer letter and tell your boss that I will quit if I am not offered the salary hike. If you are worth, your boss will retain you or else you can say goodbye
