SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9689173c059e153cb7094a15f2cca6f7cf3459a0aae5b9213e05bf71d253aab3' 
  AND token = 'feQ6EbbpMkB//11e/kN3xZN6+Uwf5NaDOKc/68OWIbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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