SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94e8f650d0177d644224210e8cf2d4ff31f2debf352146b28802bf57121c9dfd' 
  AND token = 'v29CtQ46LcwMDddFcsdYGgADRyTvukyDMS1xBakB4B4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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