SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9763f6a379284b42cfa1160dfda548bdb6d37a387ce91675016b932130b6771c' 
  AND token = 'icCyzwvlSaizj6CFdNHpYURXKukoJVCpVf0sVwbiM7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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