SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc1f414d8bb3dbb77ce0504cf7f8d40aef153e7f4bae7b5c8cde3bb8aa29f299' 
  AND token = 'BsyF26lWwtjh5ib84oGF7gxUsv+oYprVKJoh7sHTH+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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