Remove quotes from 'now()'
INSERT INTO test (1,2,3) VALUES ('$1','$2',now())
Make sure the column / field for the insert is of type date or Timestamp
If it's a text type, you'd want to change now into a string
INSERT INTO test (1,2,3) VALUES ('$1','$2',date_format(now(),'%d %m %Y'))
or something similar