SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b6c61d525abcb2eac22f72452ee7e7d47d1b1a401d0fe69841147f440e3ac39c' 
  AND token = 'U8BUqb3K5ktlh60X6ShX/bfbBdhrOaGUqiEMmoviq+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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