SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6b4ac75e8b1c2c4a52cd103d0204ba0e2db49d4c78a899191811eb98929c3f2' 
  AND token = '2TJNNWDzFBQmftwW2zanzqlAC+XGhKBLwvJkwGBPcrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

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