SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e98b83de5c1b3536456552c68013d409bd3115bd4f347d7f627b0951f5d4435f' 
  AND token = 'bPvPpp5FyVBMmyffgUs8E0EJ71qc5ARj/f1/lrlr6Xg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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