SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff9caf8cb13f45e79070574463fa81f2f672c5e8479f4b9a9399fc840621e678' 
  AND token = 'n06xigthS7VV5iKKCIONn5y+Kzsg2v6wHdLoWci9hYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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