SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cd535d233231efa3527c4bc6a63cf4800ff33e95dbd92d7a44da35dc6816558' 
  AND token = '/DyCp44oOUSMsLqvf1KsY6GMVDBK7rcrwlhzs98XFcI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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