SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dee352824e2413d5ad025a86d0ff00d9692f736de7d6bf1dafac461d7258b4f3' 
  AND token = '40MHlTiwMTFfAnAACyRJpFeK6WfIQYZPp5x0daWwbtU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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