SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6ef3610904080e9a7223ebe292725ebbfe5bbd17e2b05d21bfbfa450d950d10' 
  AND token = 'XaCYBvtigmCHB11TDMEaIcynJZu75nv/+Lh6JQ+NIaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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