It all depends on the framing of the situation. For myself, I frame it as a few of the following, context-depending on how it's asked:
* (on a webform) "not applicable" in writing * (do you have a felony?) I do, but it has absolutely nothing to do with my role (because it really doesn't). * (will the background check yield anything we should know?) you'll see something, but it has nothing to do with the job.
If they keep pressing, and seem simply hesitant, I refer them to a webpage that articulates the story for them. It's behind me, I've grown from it to where it doesn't define me, and I'm proud that it's behind me.
If they get weird for the rest of the interview, I simply say "thank you for your time, but I don't believe this will be a good fit, please let me know if you change your mind", and I walk out of there to avoid wasting another minute with their bigotry.
Once I hit the 7-year mark, that background check won't yank any database association to my legal fiction unless they wish to dig. At that point, I can simply say "nothing will show on my background check" and it's completely honest.
The reason this continues to be a problem in the USA is because people aren't confident in what they've come through. The stigma exists because employees fold over and continue letting employers feel they have the right to discriminate over what happened, irrespective of how that person changed from their experience. I see my opposing any condescension as an effort to resist a social structure that creates a second-class citizen.