SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b414235c258497e6bd22153f61d2be0bbed56e507a64e6b3e2877171d8d0673f' 
  AND token = 'SGkR1sNKctI7nc9kMdCM+2Z9IB0jNdhGbyN4P2xgdMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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