SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afa3eba9bc48875da229a4bffa1cea98d5c06f011da7b6f1890f5a39e3be1364' 
  AND token = 'UTcdyK3l2mXsZ++wk6iOSYvDp6jTgQMUT+iPBvrOqto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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