SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4c5d8cf438bdbf433467d9281abc8447e763f6ed6234a65f38486925deb60713' 
  AND token = 'MkW53lKMJSKh+vOazI0b26Ga0dyoYga8ff4V2+6V7/M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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