SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b16e98f6ec8cd7eb6344e5732fc8c8950a807e5b16f75c13cea30aeffecd0d9e' 
  AND token = 'rXwGE1VyTpDzYNrv2NZMqN+hZBHsS7BG/DozcY4XTZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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