SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '378aaef24c6d392085abf01d6a999050f87113aefb40f4a8fbe1824999fec2ec' 
  AND token = 'CwhFXZs+PrxrxblsG7tSdJOianfuBs2OfEmNgSQko4c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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