How to cut a substring from a string using sed | awk?

Question

bash

I ask for help from connoisseurs of regular expressions. Four hours of googling left me exactly where I was before.
There is a long string received from curl, I need this part of it:
...,"load":{"map":["load_id","add_time","marks","available","external"]," data":[["77458","1552767081","11.57","298","0"],...
I want to create a load_id variable and give it the value 77458, and
I want to create an add_time variable and give it the value 1552767081
these I need variables for further substitution in curl and sending requests.
All this economy is spinning in Cygwin - mintty, i.e. thought to use sed or awk, but did not master (

Answer 1

why is everyone trying to use regexps where it's not needed ...
put yourself https://stedolan.github.io/jq/