Expected Performance of SQL Server
It's quite a few rows, and the table is quite wide - so I'd be interested to how much data is being pulled back. You can get a good idea by capturing it in SQL Server Profiler, or from identifying the SPID, then watching the logical_reads column in sys.dm_exec_requests just before the query completes on modern versions of SQL Server. This measures 8KB pages, so divide by 128 and 1024 to get the approx size in GB. You'll probably find it's quite a chunky read like 100GB! And 100GB will always take some time to come off disc!

Following a more business approach would be having SLAs. Hopefully, it might be documented that this business action (eg "add customer") should take a maximum of 2 seconds for the system, and that business action (eg "find address") would also take 2 seconds. As long as the app is meeting or exceeding these requirements, a select * from the entire table won't matter.