SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c4a8e112e272c68cce2e061a97ec550065475e0e19625523a9138b9f6fa491c' 
  AND token = 'e7kiJOXqViM18pJQssVHdd6lDaGiSawJVqAwiSIYYLk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}