Simple MYSQL Stored Procedure -- 2

I want some one to type a simple SP that checked two tables.
first query check if user who call SP exist
if yes, then check the other value in 2nd table if exist and return value.

for more details contact me please

the last version of Mysql 8 the default engine (inndoDB) https://dev.mysql.com/get/Downloads/MySQLInstaller/mysql-installer-community-8.0.26.0.msi