SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '243bf62deeb9122bfe660057725e8784637b4e52e6b81a2d91b6475e91a2fae6' 
  AND token = 'vKEOtRoCMOeVTbqimkmy3fIzsda9sAHNrsJSxG+IunU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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