SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8fc67f6829e68b3f7c075954a4859397e5d4b99fe9817813a87c44aa2f958f51' 
  AND token = '2+t0vCKN/YTVqg2ajfzqeww0cypcCRLmoIlxY3JoAqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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