SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23fc1c14265804c7bb6232f412cc83e65c4cc2bebf09139b2da421e66c1ba2ab' 
  AND token = 'VIyc8XnvRphrkHOfnJFreSkzsb44gt7gsslsfNKpK9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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