SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4142b585347309942182cf7655d2e2c12a843018d9ee8050ed6ae4a661fabb5f' 
  AND token = 'vDocM2RGRmnamGYiEzJDDCWLopWS9OK89cQn/ZVbbDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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