SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd9994fc5f977cec45e6ecc4fc32bd45be9261a95e1ace0423b02904e288245f4' 
  AND token = '/dtjsLIaRGWBb9BbBz5WLuesIcYC6AimkmjAmEkzcGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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