It would seem that the option for a Russian/English keyboard is not available in Thailand. There are two Apple stores in Bangkok: Central World - Apple Store - Apple (TH) and Iconsiam - Apple Store - Apple (TH). Either of these would be the best place to ask in person or on the phone; it is unlikely that they will have a different answer.
If you search on the Thai Apple online store there are no options for Russian keyboards: you can order a Magic Keyboard with only four options: Chinese (Pinyin), Japanese, Thai, or US English. Were you to order a Mac on the online store the options are the same.
The US online store offers the Russian/English Magic keyboard and the same for the range of notebooks, but Apple online stores will not ship to addresses outside their own territory.