The scaling law for the horizontal length scale $\ell$ relative to the domain height $L$, originating from the linear theory of quasi-static magnetoconvection, $\ell /L \sim Q^{-1/6}$, has been verified through two-dimensional (2-D) direct numerical simulation (DNS), particularly at high values of the Chandrasekhar number ($Q$). This relationship remains valid within a specific flow regime characterized by columnar structures aligned with the magnetic field. Expanding upon the $Q$-dependence of the horizontal length scale, we have derived scaling laws for the Nusselt number ($Nu$) and the Reynolds number ($Re$) as functions of the driving forces (Rayleigh number ($Ra$) and $Q$) in quasi-static magnetoconvection influenced by a strong magnetic field. These scaling relations, $Nu \sim Ra/Q$ and $Re \sim Ra Q^{-5/6}$, have been successfully validated using 2-D DNS data spanning a wide range of five decades in $Q$, ranging from $10^5$ to $10^9$. The successful validation of the relations at large $Q$ values, combined with our theoretical analysis of dissipation rates and the incorporation of the horizontal length scale's influence on scaling behaviour, presents a valid approach for deriving scaling laws under various conditions.