It APPEARS that mde will filter for you. I haven't gotten it to produce a list (that I trust.)
Go into dining, select MK, Counter Service, Nov 30 (mk 11p-1a emh.) It only allows you to search up to 10pm, so I'm not 100% sure if it's actually validating for anything open at that time or just checking fo any QS... BUT
Once you select a place from the list provided, it shows what would really appear to be their hours.
Be our guest states it is only open until 11pm.
BUT OTHERS, like Casey's Corner, list the Magic Hours under their operating hours.
If you select a different date, the operating hours change, so I'd assume that Casey's is open for the EMH.
AND ALSO, from the TP site's faq about EMH:
Q: Will there be food available during Extra Magic Hours?
A: Has Disney ever let you starve? While the in-park table service
restaurants will likely not be fully operational during EMH, there will
always be some counter service options open whenever there are guests in