SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '596aedd8f6d8a982441c70efeea8768bb194b547d816e1e07ec807b40696c499' 
  AND token = 'pjiqsGpUhAboxb7VUKoOk0MPZK+3ByXa0tbaD62AIiU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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