If someone in the audience is convinced that you can keynote their program, then you are in. The bad news is that there is a built in resistance in giving trainers that chance in the first place. The keynote speaker must still touch audience's hearts and do it quickly. Trainers here have to be more motivational and usually can easily leverage exposure with that audience. Because then you can springboard to the other association markets as a keynoter, after establishing your track record.
Associations pay attention to other association choices.
In training, the audience doesn't have much leverage because they are not usually decision makers. If they just happen to be on the program committee, then your foot is in the door. Ask about the associations they are involved in. Don't even think that your program outlines will cut it. Keynoting is a performance, so show some pizzazz in your one-sheet.