It’s down to the resistance of the LR41 but those little keychain lights do get pretty bright, maybe 50+ mA. You could always check with a meter. (Added: The current will drop very quickly once the batteries aren’t new, so don’t worry about overdriving the leds for long periods. The batteries just don’t have that in them.)

I have a nice little 1x LR44 light with an actual boost converter inside and I love it, but that format never became popular. If you want a very bright keychain light not much bigger, try the Lumintop EDC Pimi. I’m down on Lumintop in general for various reasons, but that particular light has attractions that are not matched by anything else afaik.