SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52f6b308b611b1096d01e8077249a78097c7af912e936dd68834e1e951871b5f' 
  AND token = 'heSv9EM3PUgfjQKCrRYPuNMqPBQbQMDypYtIxeiJKRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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