SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c08b8a1428e61ef8f2a9e89c7d0ea92a90930855c3db3409d38fbdee980dde5' 
  AND token = '19dCcJPnWegJbIsvuZPpawcOS8LkZYz9R21BgpPO3Lg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}