Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Midland to Klamath Falls as you normally would.
These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Midland Intl Airport to Klamath Falls Kingsley Field Airport flight would often be abbreviated as a MAF to LMT flight.