Start eating in bad conditions (e.g. on your only 15 minute break during a long shift, around people/places you can’t tolerate, or right before you have to go somewhere) and eventually you’ll start feeling the urgency enough to rush your eating. Ofc none of this is particularly healthy, but it works. The other thing you could work on is becoming more comfortable with the pace you do eat at and know that the people you are with are probably not judging you and that they enjoy your company