SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d58bd23ea51a83013a45556bbb9334d8ae8a8c3a4d4349ce21149474212ea81' 
  AND token = 'prSz2/skHmGsYvIHTnOFI8ouwMs6C6x8ayxutWSZ+Jk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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