Update date field with supabase's instance date

Hey! does it possible to update date field in table to be like

NOW()

NOW()

?
example:

const userId = ...
await supabase.from('table1').update({
  my_updated_at: 'now()'
}).eq('user_id', userId);

const userId = ...
await supabase.from('table1').update({
  my_updated_at: 'now()'
}).eq('user_id', userId);

is this valid? can't find any mention in the docs.