SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3175a4620491bc701b2f4fec2e560a6937fa7e93ac51ee5f8983c0aac91f6365' 
  AND token = '3NalcMyyEmds7YIunEHsTpnU9S5Dk9hZLKDlbcj5zSQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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