SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6b2ea82ec893558cdb2a15bf3909644c0d318b69f70940f350752e97478a13c1' 
  AND token = '+gz+NRxR6WIQ/tGsg8lgfVrYhTGr9uLODgVx6Ejv/Ns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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