SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89b534218400557218b6e4b1860555d080c1df6ade7d21eda448c14c380018aa' 
  AND token = 'Rq9gqjz/ib9YbkGTiBKLOgnux79gRrCWjYJEevgg+DI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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