Required package php-imap/php-imap. It requires the extension php-imap.
Installed: "yum install php71-php-imap"
After installation, the command "composer install" runs terribly slow (maybe a minute).
ie you need a set I haven't installed (php-imap/php-imap), but the problem is already there.
Once removed: "yum remove php71-php-imap", the problem disappears and runs composer install in 2 seconds.
UPD: the problem is not with the composer, but in General with php. And only in the CLI.
The command "php-v" is 5 seconds.