SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9114cb9421361c1f117cb4585d2b50d1d28bc328f42c9cdfd5256d6ce4c53244' 
  AND token = '2zNlmDYqUSDbiK/5zRvT/yO+3l1GfXUkuHVrlEX+H2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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