Good simple concept with clean presentation. I would tell you my score, if it wasn't for me accidentally clicking it away as soon as it appeared (I was trying to click on a box last second.)
Having the cactuses makes for a better challenge, but I would love to see the spawning frequency of both cacti and boxes to increase as the time progresses. How it is currently it feels like I can't improve my score, as I managed to click on every single box that appeared and I didn't click on any cacti. This in addition to maybe reducing the 60 second timer to 30 would make for more of a "I can try one more time" kinda game. Well done!