SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77a957fbdb8938b6bc88611e1a69e311f4e42ae6e4b3387cc46111948979b49a' 
  AND token = 'OZg88iciXIGBYR7WFzcjcVhsnf2i6HE9txZ7lopzm+A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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