Just use your hand. If the beer is in a bottle, leave it so the neck is sticking out of the ice water and spin it that way (this also works very well for wine.) If it’s a can, stick it in vertically, and spin it for 30 seconds at a time or whatever you can stand.

Even if you aren’t constantly spinning it, it will still get cold much faster than any other method. I’ve worked in bars and restaurants for 15 years, and this is my go to, in case of emergency method for chilling beverages.