SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdbe9cae497cd2fde4a7bc4a9ead4bd36014351857165cda043da36bdb714e8d' 
  AND token = 'WpWL3oPCCqvlM6bKTPN7RY4lWPrXoru4QGYzoHDkq+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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