Interpreting results when IC temperature fits all categories
Technically, if you are not running exactly at 25C, you need to use the maximum value for -40C to 85C since that's the smallest bucket that fits your temperature (assuming your board doesn't heat up too much and you aren't doing something like running your board at 75C or 80C ambient), so 215ns is what you need to use. However, that only applies if you are running at 2.0V. Increase that to 4.5V and you're at 43ns.

In reality, the propagation delay will probably be around the typical value, with the maximum at 170ns since you are slightly under 25C and circuits tend to heat up when they are in use.

The other thing to keep in mind is that those maximums are very conservative in most cases. They account for both temperature corners and process variations. You may find that your actual propagation delay is quite a bit smaller than the maximum.

If you're super concerned about propagation delay you can:


Measure the propagation delay of that IC on every board. This isn't unheard of and for precision equipment there is almost always a part that needs to be characterized per board for calibration purposes. You'll need to heat your board and cool your board in an environmental chamber too, unless you only specify that it will run in spec at a particular ambient temperature.
Measure a sampling of ICs and give yourself enough "warm fuzzies" that the maximum propagation delay will be around some value.
Find a shift register that has tighter specifications. You can do this either by using an actual part or implementing it in an FPGA or CPLD and constraining the synthesis tools so that they meet the specifications you want.
Design your board so that it meets timing with the absolute worst specs. (You should really do this anyway, even if you weren't super concerned)


If I were super concerned about propagation delay, I would go with either option 1, 3, and 4 with my preference being for options 3 and 4.

Side note, if you want to measure temperature for the chip and find out your actual temperature range, you just need a thermocouple glued to the case of the IC or hovering in the air. They come with many multimeters these days and are quite cheap.