SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39c2a6f08e3ccb1b78a8a644574b4f7386678cf5277e07d6f55ef3f7fa97db50' 
  AND token = 'hdkicxsWEgKFrPJ5JifMtkI7P6YPuiitXM+0XakeXwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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