SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99f789c41ccaef8d86241ba492695eae8f55cbf439a840787f321dfcb98ea003' 
  AND token = 'qJztwLlvPsaNrZsfBpHTpYDi9j80xDbecBhYGb5rujQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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