SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b94e4dca49ef873aaa0eb745888d42304f5cebb1fbe57980d2a8de2895413f5b' 
  AND token = 'x2kTXSxSs/rh+++84CMltxV99QRWKgqDGbV86uvAll8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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