SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42dd3ba15cf5f22d234057b74a78c35a8c6e8a9dcc6404403d49e8ffc7be0669' 
  AND token = '3Pvi5WjDlDchSePM36gQzAQvmtdxAVWEu+5RefD0oC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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