SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b20409af3e6aadbe5f5cfe4ae295a528798e04879296bafbdc2f43a145cd4c3' 
  AND token = '20gTCSt0tEPuTlnwwwVXSjJd3WKRbS+q0hQEVW8IfJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

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