SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8f43476aadc026cb1ed6b05dac3a4d2158de274078548b0f741415ff53e5e5e1' 
  AND token = 'yO/kzDyvOL5E53WJ64rpxiJ5+Q+5/1CP7+z80GxwgLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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