SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '42368ab35ec43c774daff02401797877a1c74d9c3e76b1556a08d8d4560bd00b' 
  AND token = '/hVHeKL+VLn/ikiTwdyqyPWerWkIn/ufHUSaDyQg4Bs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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