SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcd5f92495d63ed7f61baa2ef265d96de921ae4f88c7b5739bd37fd457a08514' 
  AND token = 'ULatGgtWAe+RQWWwgZXuduxPq8bTyeYdMAYSEvtOGhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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