SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a8e8202dc52d33611afb751161c18efc6ab52990bb89e150702ef3d6d83ed06' 
  AND token = 'dnDOIEHHBoG/pUoBEcAtlyVReWY4DnbYDuaVUc3vdQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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