SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21ce81de70154c9637fb365a7bc9d8542b16e6e71ec9fd66a83329855a98c047' 
  AND token = 'jrT8talLy/JZExKp2/fddS3swtNfrj9nYhzif43p8hc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00050

JSON explain

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