SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '45c8644ee12055a91907444513ff8d50f7dd827575c7842b50831db9c00eeb67' 
  AND token = 'fhaltr3ghhO8/BDVeZaOSqJQ+aEX5eZgm3uGDVM2cPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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