SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c6ca39178a14ccf763d18b4b6da93069c12aec139fe772f260758d450679849' 
  AND token = 'Un4bchtGOiWvhMZ8t7wtMB4BxQoGP03mMEc5ftQsPD0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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