Yes this is a high total. But it's not high enough considering the teams and situation. 
It's rare to find the Chiefs with a healthy Patrick Mahomes as an underdog. The Over has covered five of the six times it has happened. The Chiefs should score more than 25 points having accomplished that 84 percent of the time when Mahomes has been the starter. Kansas City's offense potentially could be even better than last season with an upgrade at tailback with rookie Clyde Edwards-Helaire. 
The Chiefs' defense has given up more than 6 yards per play in both of their games and face fatigue issues traveling West to East after being on the field for nearly 80 plays during last week's road overtime game against the Chargers. Kansas City is especially vulnerable to mobile quarterbacks and Lamar Jackson is the best running QB in the NFL. The Ravens should encounter little resistance on the ground, which in turn will set up Jackson's passing. The Chargers rushed for 183 yards against the Chiefs. The Ravens are a far better running team. 
The Over should be helped, too, by rules skewed to high-scoring games and official's calling less penalties this season.