SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1aaa14b75360e3a432a24b71232663838e5868b50b8415311373f3a628720d32' 
  AND token = 'F6XcMFWLLQBVwQeTX4faPTY9RLDe6nUresQDAd3/a1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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