SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f8f262c7ee0ddbc9f1074bb5ee1482ce521b353d046937f4ab14bbee6915969' 
  AND token = 'MYNp2aLQde/n3ej2mA4fQzOlg27MxmmpJ9lDiVsvdFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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