SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76c8d561fb134ad7944ad3edc2c92b1b643e59271dfdec1a84f13618596ae361' 
  AND token = 'b00s3N7KCmI3edDauil91qNn82hosfpQl1ek2ugysxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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