SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a88c1a692944cab187100f7d319d6f3a656cb72ae3b8a13240fe2351c4eaf15' 
  AND token = 'z1KruKnvo9GPomwzLE5WADUtbDfay8QqUWGaktONQuI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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