SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b292fabc6da4667d2642c39b4720e89f148da92dd4d35b027fa70412b9084acf' 
  AND token = 'EHRg4PznwB7BNoHdxhC0UnCeXVsTjd9dX+OrkQn0hGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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