I didn't see these in use, but generally, the "Good Only..." or "Playable Only..." type chips are promotional chips. Perhaps given out for a 1st timer to try the game (but not cashable)?

The 70-cent chip was the cost of an entry-level keno ticket in those days. If it was sold at the keno counter (10 for $7.00), it has the added utility of exact change for each game, rather than giving back 30-cents in change each time. Saves time for the keno writer.

Another possibility: the roving keno runners that run tickets for you while you're in the coffee shop might have used them in lieu of change and/or to pay small winning tickets and encourage re-play?