SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '29841b1207f69829305568fc6e504685c9f0b9dee9ae5fd4648f8d0b62d10a1a' 
  AND token = 'sCavK7jmNiB9ZcGfMdmPyg0yqweKMub7Bl+xZc+rpXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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