SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0255abdff4076714de7f42ff0447062d2e9f2c28b7275fc53615565158c3b761' 
  AND token = '5RpSGhRrMa1/Gao5zQzUrzoB2MkUA8h0sAvDsaleLlg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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