When flying from Bangkok to Kyiv Boryspil Intl Airport, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.
Bangkok Suvarnabhumi Airport is BKK and Kyiv Boryspil Intl Airport is KBP. These codes are created by the International Air Transport Association (IATA) and airlines use them to identify the departing and arrival airports in the flight routes they service. Bangkok Don Mueang Intl Airport (DMK), Rayong Utapao Rayong Pattaya Airport (UTP), Hua Hin Airport (HHQ) are other airports near this flight route and their unique identifiers/IATA codes.