It's a tough one. It is obviously a prize token. But I couldn't find any information specifically about the Keystone Development Co.
What we can do is narrow down the timeframe a bit. The New England Building was built in 1910-1911 and was home to Merchant's National Bank from 1911 to 1969.
So it can not be any older than 1911. The upper 5 floors of the building were used for a variety of different businesses. With the number 240, I'm guessing Keystone Development Co. was on the second floor.
Now in 1958, Topeka went through a fairly hefty Urban Renewal program. They designated 37 blocks as the Keyway Urban Renewal Area. Many of the buildings were considered slums and were torn down. 70 Acres of the land were made available for private purchase and redevelopment. So that coin may be from the 1960's.
However, there was an earlier building boom around the 1920's. So it could be older.