You should declare -A
(capital A) an associative array in bash. This is the correct syntax:
$ declare -A my_array_filename_var=([.phpsh]=10 [.php_history]=20)
$ echo "${my_array_filename_var[.phpsh]}"
10
Or
$ declare -A my_array_filename_var
$ my_array_filename_var=([.phpsh]=10 [.php_history]=20)
$ echo "${my_array_filename_var[.phpsh]}"
10