SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c638fae96016e7535a84b4687183a2bb340051359b426bd400c9f6040acedd9e' 
  AND token = 'j+nKcMEC0mz9W9+Z7RK6gYacueX+3YGWgtvP0Nk2v8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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