SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fc36396f5c86878071df3ec489b1057b7bcfae7db1c221d016475d1976c5d06' 
  AND token = '+sUm+j4+QTBJg+jHQPHMwJxmqb5bK9Fy3to2cGxpmLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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