SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '923ca134cd6d98a702d73353e50823d7600530b83c354885b8c7158091968231' 
  AND token = 'k3Yehsf1IZkXrR0GAl8PoHFrndVuzoxnd/bgsT+Apxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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