A system includes a subsurface safety valve and a lock tool. The subsurface safety valve is installed within the production tubing and has a main bore delineated by an inner circumferential surface of the subsurface safety valve and a lock profile machined into the inner circumferential surface of the subsurface safety valve. The lock tool is movably disposed around a conduit and has a locking dog configured to engage with the lock profile of the subsurface safety valve and a conduit seal made of a swellable elastomer. The conduit seal is activated by an activation fluid and has an expanded position and an unexpanded position.