SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d8e1b97a15475e43f0a5a255d151bda2b1f317a586f026977b656aa4dc066da' 
  AND token = '3xyIBBGh8xP3FBZ5Cji2o+LBMpwXtdbbBZF28K3y2uE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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