SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a367e21dd7e8f49012b602bda5ccb465cf82953781aba7e148cf754bbea06f6' 
  AND token = 'EmVBiDf/9ZHRAjcmOJXYzVrQL/JxKIoQ7Hj3ygIzIj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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