SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da6d69e2836bbadf987e4ead0fd1bbae47524631b407eaba63cb1e3278ff3b7a' 
  AND token = '9tvboj4cFMoBL4li0XwKxldUpS0WGjPUxjznaTnInnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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