SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7b524f3837b7a98540fd2673be189ed2926f005cd2576be2ad75543880b1aff' 
  AND token = 'QrOWNXJm/KwPU6KMw63XhbHY4awjZY+0uDGsewcLxGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}