SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7a453fc66bcbca68d3f550bce85015c4a27cf1ac5647d92b6c9bdd4980eda72' 
  AND token = 'rUIKuWU+gp9pyqVsArbhev/ZdgoTlNgFxq0ooBRohDA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}