SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9db1ef73ad0168b7deed16a9d9e55d25f7d4818a934f8efcfbf9fef9c6af876' 
  AND token = '+FeiDjkZ+1WOMgpvoMV/FVQuLrvSul4nQE6nnBsvq8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

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