SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdf6d7bbb54b1013d3f4844fc2f3f941bde10c467f7db54b58f81bc5ded7d315' 
  AND token = 'L6MBkGKGD/FL9KyhbVmlIzSOyIkZd/+JAmpBxOTnVCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

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