That is good news. Checking the MMIO Lock box disables the secondary turbo power limits. Intel CPUs do not really need multiple sets of power limits all set to different values. Best to keep it simple. Disabling the MMIO power limits is a good thing.
https://www.intel.com/content/www/u...-12m-cache-up-to-4-40-ghz/specifications.html
The Intel specified base power limit for a 12450HX is 55W. It is OK to set the turbo power limits lower than this value if reducing the maximum CPU temperature is your goal.
For better performance, I would set PL1 and PL2 to a minimum of 55W. The recommended turbo power (PL2) is 157W so you are not going to hurt anything by increasing both power limits to 55W.
The Intel 12450HX is designed to run reliably with maximum core temperatures up to 100°C.
Reducing the turbo power limits is not the same as undervolting. You can also use ThrottleStop to undervolt your CPU as long as the manufacturer has not locked out that feature. Post a screenshot of the FIVR window if you need some help with undervolting.
I recommend updating to ThrottleStop 9.7.2
The new version finally lets you set different power limits for each profile. This can be useful if you like to use different power limits depending on the game you are playing.