SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '23f754e6775a68c012ace08027abc0491b8f4462832fa9795f2342b853b7def2' 
  AND token = '9H9ZPEd5TopMVlDknpPuscfuO+7zJJ8evhad/iCCA/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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