SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9bcd8c7d68612903e60d5074f681370338e5cb95d5c0510243297da58a190b44' 
  AND token = 'nuy2Hea5UAvZzNXwAlsKetYYs9r5eYt9dtMvNANVHn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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