SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39206e04110effbd92ac619120a6cf0692ae79b9f43121e0d3197fdb74fa155d' 
  AND token = 'oGNj3LVeexlZvMwte+/HGMEstm6WFncOGdWslQVsxls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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