SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c983b4bd6a038b20ec44f073157a6cf111b97edbd918939c4fbe6e24c3509983' 
  AND token = '3RgHqZsc1ZF9OpdsuI19trxCUdPjpUJavbk6gRgmlWA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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