How many rows can an SQLite table hold before queries become time comsuming

sensors
 - id (pk)
 - name
 - description
 - units

sensor_readings
 - id (pk)
 - sensor_id (fk to sensors)
 - value (actual sensor value stored here)
 - time (date/time the sensor sample was taken)

SELECT * FROM sensor_readings WHERE sensor_id = x AND time > y AND time < z