SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b597160efc167216a905d7497c15af17d958a58c1877dd2a6c93201b2a746500' 
  AND token = 'JnqcYhryzEmvDNiFifVA4AYPqq2ai9e0GP4cVb5Shpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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