SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a98fb88b4b5373d9873ee0542ed1bf98f3845141c1c41a74f10754a10d992c34' 
  AND token = 'm4tzoNumVquONXTSrSLtiaBet3ZtQRx5IFNNatynsjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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