SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98e746dff0fca92e371eb466276f98ea0f51c9303efd79d278e43442bfacebb3' 
  AND token = 'mQzPmhhWT0c10XOYoa5FwFV6WYBrn+Kt43AXBgVe75c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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