It's now possible to do:
SCAN fleet WHERE "properties.speed < 25 || properties.speed > 50"
Uses javascript-like syntax using the https://github.com/tidwall/expr package.
Automatically reference fields and GeoJSON properties:
SET fleet truck1 FIELD speed 65 POINT -112 33
Can be queried:
SCAN fleet WHERE "speed > 50"
SCAN fleet WHERE "id == 'truck1'"
SCAN fleet WHERE "speed > 50 && id == 'truck1'"