Note for Strapi v4 users :
use the config/plugin.js to update the expiration time.
From Fix JWT using wrong file and structure by derrickmehaffy · Pull Request #649 · strapi/documentation · GitHub
module.exports = ({ env }) => ({
///...other plugis
'users-permissions': {
config: {
jwt: {
expiresIn: '1y',
},
},
},
});