SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4d84921ffce78649aa901800188cad81a19a78320e6581427dace677190db864' 
  AND token = 'eVeljkFuplBsIpzB8yU+B0o5ZD4SDWS3p+685bkRVL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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