SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '246e3997dca15da552c24e89abcde2a6585905d7963a9d6e4105daea148f8dae' 
  AND token = 'kFJFCGEZvV/XdWoxcN4h5eK7IzGdIt40+uHKeeF03UM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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