SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9991e26311287faf0ea6fcf4cc510b815e09154daefd66a4725ac74f31f62484' 
  AND token = 'odLlzoYggUmN7JQwFNlAC2+tDYKrpwx5BuwjulC5EPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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