SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '7794399f2332f05a73cbf95984fe3eca20a53ae816e7986feb22cbda86a08dc6' 
  AND token = 'RkIQiZMY5DRzBGulWyhOMwVco2husYXeH/bzRClVkPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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