Left crockpot unplugged for about an hour
It likely depends on if the food came up to 140°F (60°F) while you were still at home, and how much it cooled off during the trip.

Basically, your time in the 'danger zone' is cumulative, so it's the sum of:


Time to heat up to above 140°F (60°C)
Time from when it cooled down to below 140°F 'til it go back up to 140°F


So, if it never got up to 140°F, then it likely spent 2 hours in the 'danger zone'.  (40min + 1 hour + time to get up to 140°F), which some people consider to be right at the edge of acceptable.

... but if it got up to 140°F in the first 20 minutes, and it was well-insulated so didn't drop below 140°F until 30 min into the trip, and it came back up to temp 10 min after plugging it back in, you'd have had (20min + (1hr - 30min) + (10min) = 1hr ... which is well within recommended times.

These also assume that you didn't take a long time to get the chicken home from the store and/or leave it on the counter for 30 min while you were putting away other groceries.