SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6b4004b25a5ad37a18371e48673fb9377788b9db46a8b19d3ad98d7ba355843b' 
  AND token = 'MOeZDwOwXRDPb3bmiZayJSbno6YiGJVyvecPLhnbETI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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