SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e1fee0b6397455375f087a3357212e9fb388c7c5b41b15528f2c8735a67f970' 
  AND token = 'JdO1tZu3iIios5FdUrJvDAyrEjlRdJOWT1h4ysu0ymc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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