Thank you.
This is what I have done: disable automatic calibration and using ESPHome info, created service to calibrate manually. Placed the sensor i empty room with opened window for 1 hour and then forced the calibration. Worked well! The readings were reset to 400 ppm and then when I took the sensor to another room with people it shows reasonable values.
This looks like process to go forward! 
BTW, I have noticed that MN-Z19B sensor seem to perform measurements every 5 seconds (at least with this period I can see the “red” light blink) regardless of the period set up in sensor configuration in esphome.