SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '216ec0c0bfe441420b241cf98866baa8bed998ab866301924f511918c598dcdd' 
  AND token = 'xDtEHmekj6qeyDlCSQBQ6kZKoIihfwj/lQuK+vx2uN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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