SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e0f2e6361ab6715994da54d40fd6e4a27f0d4df9c1bde794c291a056830dece' 
  AND token = 'ZLZplNERWM3Pa4mcMUc1lAEOfNsZ0LcJanB+qqXXxuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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