Source: https://stackoverflow.com/a/45241314

.htaccess

AuthName "Protected Area"
AuthType Basic
AuthUserFile /path/to/your/.htpasswd
AuthGroupFile /dev/null

SetEnvIf Request_URI .* noauth
SetEnvIf Request_URI the_uri_you_want_to_protect !noauth
SetEnvIf Request_URI /another/uri/ !noauth
SetEnvIf Request_URI add_as_many_as_you_want !noauth

<IfModule mod_authz_core.c>
    <RequireAny>
        Require env noauth
        Require valid-user
    </RequireAny>
</IfModule>

<IfModule !mod_authz_core.c>
    Order Deny,Allow
    Deny from all
    Satisfy any
    Require valid-user
    Allow from env=noauth
</IfModule>