SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff29302bdee8e974f0fcea28ce06efc896842347af24be5d053bdc0ec50a2e0f' 
  AND token = 'SgTDDlpDFERb/xmMVOIJhIxN8tr3aU6lK+5N9u7L1Fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE Impossible WHERE noticed after reading const tables