Section 4B. Whoever lives or derives support or maintenance, in whole or in part, from the earnings or proceeds of prostitution committed by a minor, knowing the same to be earnings or proceeds of prostitution, or shares in such earnings, proceeds or monies, shall be punished by imprisonment in the state prison for not less than five years and by a fine of five thousand dollars. The sentence imposed under this section shall not be reduced to less than five years, nor suspended, nor shall any person convicted under this section be eligible for probation, parole or furlough or receive any deduction from his sentence for good conduct or otherwise until he shall have served five years of such sentence. Prosecutions commenced under this section shall not be continued without a finding nor placed on file.