There are 15 Lockbox in Aberdeen & 15 in Kennedy Town.
NOTE: Later on in the game you will meet King. He is in the music industry and wants to see Hong Kong. You will take King to a bar, you will be asked to find some girls. There will be a girl by the name of Ilyana. After the mission you will be able to call her and ask her out. She will offere to race you. Once you have beaten her she will award you by displaying all Lockbox through Hong Kong on your map. To view them on your map, press and it will show all collectibles. Collectibles in white have already been collected, collectibles in grey have not been collected.
Here is a great video guide by Predni showing all locations of Lockbox in Hong Kong.