SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '816ef56c29f912f779c561635b63e145a87adfe65dbb18bd7b2d8040ac4fb5ab' 
  AND token = 's0XeAUFR0BEd8EBvzXEGvktVxSYEbhAsXdulntX4Fuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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