SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94b0ff07219462bd5fe76eb09bb11053b18bdf138e740f26c7b54642cb97fcdf' 
  AND token = 'b8GBsAjbdzLjhdTzfSGghIUzSq8/9K2VCilFUof8atw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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