SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81108652c92472f70488870388109fa57dfdd5a9521ee7e3ac4736d36a3bef4f' 
  AND token = 'Kg5TLXTknEQJIYhWgevJH0Yahj+tX/JzHlk9/8OzwKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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