SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b1f16bd6ff6385e0871d87c05dd57e41eb6f93236dad2afe5995c513084ca97' 
  AND token = 'OR0b4pqtAQBjZ/mAg6nzTH7WPZIXBd4+8REGNLcNfYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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