The default keymap is commented out at the bottom of the default config.yml file that tiny creates.

Here is a minimal version:

key_map:
  ctrl_a:     input_move_curs_start
  ctrl_e:     input_move_curs_end

Each entry in the map is made up of a Key (single or combination) and a KeyAction.

Here are the available keys that you can set or override:

• backspace
• del
• end
• esc
• home
• pgdown
• pgup
• tab
• up
• down
• left
• right
• any other single character or number

• Alt + arrow, ex. alt_left
• Alt + character, ex. alt_c
• Ctrl + character, ex. ctrl_a
• Ctrl + arrow, ex. ctrl_up

Here are a list of the available KeyActions:

If you are using a non-US keyboard, such as AZERTY, you may rebind the tab control keys as follows:

keymap:
  alt_&: 
     tab_goto: 1
  alt_": 
     tab_goto: 3
  alt_': 
     tab_goto: 4
  alt_(: 
     tab_goto: 5
  alt_-: 
     tab_goto: 6
  alt_è: 
     tab_goto: 7
  alt__: 
     tab_goto: 8
  alt_ç: 
     tab_goto: 9
  alt_à: 
     tab_goto: 0

You can also rebind characters to other characters with the following:

keymap:
  q: 
     input: p

This will map the q key to p, so when you hit q it will input a p in the text field.

Code reference