SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21d44310b07d09a9061e42e3ae35eea77210136854c1150a3fb8f1ab374cd16c' 
  AND token = '/gu8YviVnfLob+WXqhTfD1TzFuF/Yg9RxeBdbR4XHww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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