Keel
The right way to fix the leak is to lift the boat off of the keel, clean the keel and keel stub joint surfaces, have someone with a trained eye check to make sure the keel bolts are sound and have not been stretched from the impact, re-bed the keel to keel stub joint, torque the keel bolts and the boat should be as good as new.
However, depending on the impact it may pay to hire a marine surveyor to inspect the FRP in front and behind the keel stub for hull damage. That is where the most flexing occurs from an impact. If so those repairs need to be made first before finishing the keel re-bed. Most quality marine insurance companies will cover these kinds of accidents, less any deductibles.
Then again, depending upon how much the boat means to you, how long you plan on keeping it, others might suggest that you clean the open joint area, squirt in some sealant, re-torque the keel bolts and call it good. Then later on sell the boat to some unsuspecting newby.
Terry Cox