SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dcb70560186ae486fb434ec56e37280efe17135c8e189462f4292e7a32d70fa' 
  AND token = '6RGIiigLSnOECmuBqpzWwOWD5gRPTaWlEe9iOsUWnqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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