SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c95d34aeecee22c860f9006eae3a429b10fa261af673392dac329ca0e2c3e2d' 
  AND token = '0yngd+F6vEihnIJOKTTVdzRz6uuRzpL7O+u8Q/6scCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}