SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dfdce9c03050f3c02925a2520b56681d7e7cb8d672648311d19a79802e52f5a' 
  AND token = 'Ls4pDjFWcii9qNFyvTw8fPGLkUVGzcGSuxxdhCtvQjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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