SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92ac3d124059fec62586fedfa395e815fe01bd430a05276dfedf50b0c51017ac' 
  AND token = 'lfnYTJ+tyXQKRJFNsR9Yjpxog+RatGDUkf1olr+ysf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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