SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '56ffc2b241015ba7915a01db393f3cd1fd5af12f43b7c0b301badc199d9119d2' 
  AND token = 'iPlvVvJnyMHWGWR9kjNLHsOUst9ARytzEupBZoKgBek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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