SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '398aaae51d7ab284e520217d5917f3eb1c0092948227c0a905fc3ce01c94aab7' 
  AND token = 'jUebUrj5fM5ooc6AmFhLijOvPixW/EDRSSjSBJXrMtc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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