SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '707f63603c356dc74add20029a9f097deae55180cf0e5142c73dec423c681902' 
  AND token = 'SLd+2rmth57kd2UhZKkWhTNNhwTbyvFazMlstnH/nUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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