SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f8f9a9c2b11f038b6326cde49502b8bb2653f7e64adb05dde40fe720b9a6636' 
  AND token = 'WHISzDvoWCXLWgwroP5YH6pPxi8OnhRPzVSuFYLqM+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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