SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '399fe319a262d940779baf765368a01e27bf6948a031c00b7c294446d42b4faa' 
  AND token = 'qQp1EX1VKlxsvcs5IwU+AWgZIMZlG+jewI1RgS3eo08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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