I can remind of a few technique for pixel laser, most of which are suited to animation, not to still pixel art.
A) make it flicker. A white line displayed only on even frames at high framerate (1/60s) will look "immaterial" and thus more laser-like
B) make it a "plasma beam", with bubbles flowing from time to time
C) while it flicker, change its color.
D) make it fast. That's the nature of a laser. It doesn't bend, it doesn't propagate. It's moving at lightspeed !
E) make it reflected when it hit a shield, make it "heating" the target when it hits a target. I'm unsure about what happens to the target in your example.
I also note that very thin lasers can do a great job