SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8515fb03e922b3a7a1f05f83b17bae6ffd9504450cfd6d1f31e46c645b1847bf' 
  AND token = 'KdXuJL0Zbqz3+X7ykBcIV6x8YBUzZ+3k+OJc+h6vM3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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