Hydrolysis under basic medium
Going by the mechanism of hydrolysis under basic medium, the lone pair of hydroxide ion will attack on C=O carbon.  

Due to the negative mesomeric (-M/-R) effect and negative inductive effect of the nitro group, the C=O will act as a more electrophilic substrate as compared to the one which is has ether substituent,  

(which due to its +M and +I effect will reduce the electrophilic character of the C=O ),
will be easier to hydrolyse.  

The effect of solvation on substituents is less likely to tell which compound will hydrolyse easily as it is not the Rate Determining Step of the reaction. So although the observation is not wrong, its still not the deciding factor.