Score gained per match does increase over time:
Difficulty scales over 3 minutes, reducing time gained per match (from 8s to 2s) and increasing score gain (from 1x to 3x).
Then there's also a second bonus based on the number of shapes matched which scales slowly but infinitely (linearly).
I got to 79k in about 12 mins 40s, you can see the footage in the game page (it's the video linked). :)