SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2103fc6ad8deb853fba64cdb0cb20eab21496bfb930a23f754699b9c9b5fe72e' 
  AND token = '/B5X8XWLwctHAhRXvxnFgcUh7NHJ2eJvwwkqzXI8WPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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