Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states the following: It is absolutely fine to read the Qur’an at lunch time; there is nothing in the sources to indicate that we are not allowed to read the Qur’an before zawal (sun’s zenith). The prohibition is limited to performing salah, for we have clear statement from the Prophet (peace and blessings be upon him) to that effect.
If it would have been forbidden for us to read the Qur’an at any time, then the Prophet (peace and blessings be upon him) would have said so clearly, and we would have received reports indicating this from his Companions (may Allah be pleased with them all), who were ever eager to transmit such valuable information without fail.
Since there is nothing in the sources to indicate any prohibition or undesirability in regards to reading the Qur’an at the time mentioned, we can safely conclude that we are allowed to do so without any inhibition.