SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f769625fa2d6f13da03df8558e1d8535e230190660d888023dd2e99d49c76c6c' 
  AND token = 'oI2yWmTSl4cXlqZxmquEhFWknx+NwBgtKF9CM0MqQvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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