\[ \boxed { \left ( a{x}^{2}+1 \right ) {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) +ax{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) +by \left ( x \right ) =0} \]
Mathematica: cpu = 0.033504 (sec), leaf count = 52 \[ \left \{\left \{y(x)\to c_2 \sin \left (\frac {\sqrt {b} \sinh ^{-1}\left (\sqrt {a} x\right )}{\sqrt {a}}\right )+c_1 \cos \left (\frac {\sqrt {b} \sinh ^{-1}\left (\sqrt {a} x\right )}{\sqrt {a}}\right )\right \}\right \} \]
Maple: cpu = 0.016 (sec), leaf count = 61 \[ \left \{ y \left ( x \right ) ={\it \_C1}\, \left ( \sqrt {a}x+\sqrt {a{x }^{2}+1} \right ) ^{{i\sqrt {b}{\frac {1}{\sqrt {a}}}}}+{{\it \_C2} \left ( \left ( \sqrt {a}x+\sqrt {a{x}^{2}+1} \right ) ^{{i\sqrt {b}{ \frac {1}{\sqrt {a}}}}} \right ) ^{-1}} \right \} \]