SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53df06b7b23380e764c8aa024e325181ea56f22bd52ec36e23dd9d607c7e7373' 
  AND token = 'mVQGk2arKiaviIPnxuK11FzF0T69FLE0/qBQBqZzZMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00062

JSON explain

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