SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35ed7a9b4d270a1ed24b604d27c5002c878dd9bb8b5ce5f4f0ed9b47d314e9ca' 
  AND token = 'zCyKd4UHowQv+UMvLQRp7at9GptljlZFUhw/CkGFZXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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