SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '669ae465662ab00f5298c40be2dd8ef7d85cd536fee706ea0dd3c2fe4da9e670' 
  AND token = 'NqWJpfFhftqhscqifWeZxlhHXWqGM/G8+q//beMjWN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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