SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9797f316a2fcfd22baea80a17b6bd27d038128117b8ea14eb5414ab3ed099464' 
  AND token = 'XD9WF5kMOC3RST1lZW0QTsSsDIC42tbaZ6fRbmPYYYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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