SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b576aac2c103a463a83bf9821d29cb1d9a7ae468b9b4b509156f6d5475640a18' 
  AND token = 'vu9YLsKGZXSX0wX1IWPtSSB+8tpyf56uOQfHr6VnJvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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