You are using wrong performance data. You want to query a certain performance counter of a given service. In your case the service is CPU utilization and that service has (at least) 6 different performance counters. You can see them either by doing
OMD[stest]:~/var/check_mk/rrd/localhost$ cat CPU_utilization.info
HOST localhost
SERVICE CPU utilization
METRICS wait;guest;user;steal;system;util;cpu_core_util_3;cpu_core_util_2;cpu_core_util_0;cpu_core_util_1
or by looking in the GUI (service’s detail page):
Pick the performance counter you are intrested in (e.g. user) and then:
OMD[stest]:~/var/check_mk/rrd/localhost$ lq "GET services
Filter: host_name = localhost
Filter: service_description = CPU utilization
Columns: rrddata:m1:user.max,1,*:1593883300:1596568904:1
OutputFormat: json"
[[[1593878400,1596571200,7200, ..., 38.1785,27.5616,...]]]