SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68bdc22ddd76a539f075d8f64528934ab400983caf7ae1aed31144316853029d' 
  AND token = 'kmPMqZgPna8oHGyNNK6nLuOJe/bt60in+SJeiWk/umw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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