SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f57a08db99a94c2f2343c3bebd38c57af82f689124c033aaec6dfedbc9f55be5' 
  AND token = 'GusZRgm9a46QmmOq0ZgEMZEvPOM1MKIHUNfbGKU7EWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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