SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23ba7d68795c077ede115796279ed46a9e68824861f920f8d0e73714b1a212f1' 
  AND token = 'riSULOkrTVZHyxqoO/EpVKUIdsSJ1x77eflviUk+Bkc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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