Samuel French's play catalog is listed by number of characters. The two-handers are near the front.
Do not overlook a scene buried in The Women by Clare Boothe (Luce) between the housekeeper and the lady's personal maid. It is a scene heavy on exposition, but it is two women putting their feet up at the end of the day and commenting about people and plot developments. They can be any age. I don't know the running time.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher