SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2c1fe24793ef55353450831f0cf926ef1ef923b553d0217d203353bd64f86cef' 
  AND token = 'uTjF7tDglQR9miTRzc0yJ3UR3ArfauquLMUkU5V24kk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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