SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4821636d59ca6681890a238913ee2c5f2af2a5ab411e51ec9ebda9197170b214' 
  AND token = 'laRNDUFO5aZhp3LrTMEiQS24BoQjVassRAEGZF6bZ8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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