SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bfeb5798f3a66ded2ed58c0bfbad734daaf6d19b3233ea1394c1e38114deb388' 
  AND token = '2/ED54NgUfrZgSUM4ol1lS9CdyQVbiJ+PrVqv3GnqDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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