SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43bf86b6113127b8d67e6dd88ed56d9af7efc4810610a666c41bb440209c0c2f' 
  AND token = 'S2UY7CnizaczkJjdVsg7qJV0BHBi4pOJGqlCvbhk37w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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