SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26fce6177d345d28dad5bcdb02a36e1c9e7abd45e5e4aebd992113cd16c75619' 
  AND token = 'Vd/xO/hVbyZxAYTYv72EBEEc2Af0iIyAcuQQtD0vCCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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