SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c37d609dd61b58059bc41477ad79bb23759721d405d2dfc498a9b915e37c98d2' 
  AND token = '4yqngWy9vwF4lwmWSEln4sDyGaPBQ3lXTEBUZZ6iMTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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