How can I time SQL-queries using psql from command line?
You could use the shell command time

postgres@db:$ time psql db -c 'SELECT 1'
 ?column?
----------
        1
(1 row)


real    0m0.108s
user    0m0.040s
sys     0m0.032s


Or, to combine a meta command with an SQL command, you could pipe a string to psql:

postgres@db:~/script$ echo '\timing \\ SELECT 1;' | LANG=C psql
Timing is on.
 ?column?
----------
        1
(1 row)

Time: 0.000 ms


Per documentation:


  The special sequence \\ (two backslashes) marks the end of arguments
  and continues parsing SQL commands, if any. That way SQL and psql
  commands can be freely mixed on a line. But in any case, the arguments
  of a meta-command cannot continue beyond the end of the line.