SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '876786ae911523940cdd0b7f84db941326800cf57bcbbbc8ff8d6206ff0467ee' 
  AND token = 'xqtLYl17yBZjDyYEOw6hFWNfhAdoGo41PaTLfYIWXPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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