SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '59a3d00177be8e7275e6563ea4d5db8f6a3dbba4b610639aab5d62e273329d6d' 
  AND token = '+F1SXw/omVjfNQ6D+848kyyHBLf+ByGBfF2AuylP0rQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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