SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a66b84f7272b61483a864b12d83385fbcef5ce9277417be402a02b47545d2cc' 
  AND token = 'r64pa9AQN9KvvcvXYuEKJ0SwUa/pTxL+OjMtONG0Yeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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