SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a836dbd91458cda955a42380a9eba482e3b8fdacfae78cbc9e96fed552a7ff37' 
  AND token = 'kmDde7K28jLuRAJ7dsIbL31X3RT+zw89GbHtf1L4dxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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