Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Lombok to Borneo as you normally would.
Great question - LOP to BKI just means Praya Lombok Intl Airport to Kota Kinabalu Airport. Now you’ll know what these unique codes when you look for flights! Kuching Airport (KCH), Bandar Seri Begawan Brunei Intl Airport (BWN), Tawau Airport (TWU), Balikpapan Sepinnggan Airport (BPN), Miri Airport (MYY) are other airports near this flight route and their unique identifiers/IATA codes.