SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92b8e6605461c7dd9a69a7ccd1183b143aeab9e5409e990ee53e083c7993b445' 
  AND token = '+9p5lYG6A0Y/d+UjkEd3xeb4Ebrn2LDKqSWIrErLYI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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