SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6931dad71afc519df3b618365c3a2f11592b27fc7a91838941549d633268d91a' 
  AND token = '4QXGQygcC1s6Wue5h38Goy7j5knsuxnMHqgJKTL45Jc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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