SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '557e1a630690b9eefe9533617ce9bc055d112bf6573d32984c26feb581830b7f' 
  AND token = 'kaRgRBZejWH0vpKJ3v9Gx6ISgrszT1Bjo5P4y76JEVc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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