SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7b2fa7de99ee52c4fd31dadc69d20623e5e55f854c706a2ade54f149132bfb54' 
  AND token = 'UFOB0Hh29g/KXIlqBBGjRdY24wD2ZTufDJWMGfudvho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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