SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db6bd399023c7759f626428ac8f74adc075472ff2eeb8d9a79df4daff7c06f85' 
  AND token = 'h6+1SOu7wMreB8XZkBgb59Yj4vYEGA9KcVdEY1T70Pg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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