SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '282d77db9ccb978942ff04426829c639ef183b8c190932febbc7a49d9063e171' 
  AND token = 'L281lokOnlw0Vml87vWXaYmWZ7/SwugvlMBwRPdoPQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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