SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ef6eded866cb44a6ac2fa797bced89cae34d0c7ed6290ff52a708da680d72c3' 
  AND token = 'jM7hzAVu6Ckv9bPmqBqDetlXhlp+nkSWnMvsFlXDetQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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