SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1978a216a8bbde83c1e2b353991797bb3df2815e7cb05e3118c1ada093dc8fe9' 
  AND token = 'emHrhFvJgtcW1pOwJpxEQACTsYT+1frLGYuB6aGmL2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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