SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '203dfff275165afab47f099af788ba2fd72477be0214a11c55ffc9bee78638d9' 
  AND token = 'tLUxnaXGgtMBGdbYvF4C5wKvAnB+rGsl8stWghsHmEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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