You could use ismember if you want exact comparison (i.e your 0.786 is to be found exactly in the spreadsheet down to the last decimal value).
New in R2015a is ismembertol that allows to specify a tolerance which works better for floating point number (bearing in mind that for computers 0.1 + 0.1 + 0.1 is not equal to 0.3, when using double or single precision numbers).
m = xlsread('somefile.xlsx');
A = 50; C = 59500; E = 0.786;
rows = find(ismember(m(:, [1 3 5]), [A C E], 'rows')); %find exact values
%or
rows = find(ismembertol(m(:, [1 3 5]), [A C E], 1e-4, 'ByRows', true)); %find values within tolerance
edit: a few typos
