How can I see if a timestamp is before now or empty?

I’m trying to see if a timestamp is expired. Which it would be, if it’s before now or empty.

exp=1662023095
NOW=$(date +%s)
if [[ -z $exp || (($exp < $NOW)) ]]; then
  echo "Update token..."
else
  echo "Token still valid!"
fi

The always echo "Update token…". Can someone tell me what I’m doing wrong?

>Solution :

found in the man bash:

When used with [[, the < and > operators sort lexicographically using the current locale.

Give this a try:

if [[ -z "${exp}" ]] || (( exp < NOW )) ; then
...