SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58f6b18e104f1095407ebe10d30997085c92c9a742972bcc7a1646d975de0900' 
  AND token = 'rcXe9oWInhBuV/33oc5qXaMpyuSiAV4qqZQ2XGiob7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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