SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81d8d8489ab1f08d77ddebc58a4f311db4177171479181e5840f1d5a8da46e95' 
  AND token = 'n2qdUyziEiD33WiaA/xSEYw9PmV2CFCK2F7GNXBhLAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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