With 1.7.x, you have to write some type of script that queries the MySQL data and converts the results into line protocol so they can be written to InfluxDB.
If you were using InfluxDB 2.0, you can use the Flux sql package and the sql.from() function to query the data from MySQL, transform it in whatever way you need, then write it into InfluxDB 2.0 with the to() function.
