SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '836c6568967b6e93abef7b954b38e502db6eee54225aa8bea7533cc334ef0530' 
  AND token = 'MjUFn5SnBeGUraQyaxlvpDLZPQEqEnu7mFklCahqN3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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