SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0821f7078ebd9a6faf3e2e58a9731b1097d9c4a058b8879c8f53515f3750e61' 
  AND token = 'ZXqWnMs+YgV7V4q6ib4cJBwFEKDUJtXD9gLLHa9Wzw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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