SELECT 
  `data` 
FROM 
  cscart_storage_data 
WHERE 
  `data_key` = 'dev_mode'

Query time 0.00086

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_storage_data const PRIMARY PRIMARY 767 const 1

Result

data
a:1:{s:13:"compile_check";b:1;}