SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '1b5121cba8f11be322926668c2946031af8bdb0b2c5e4fc6abdb0be38584b64c' 
  AND token = 'fhzSeB85p5kUIIBiePxuIWmviYdIHinkD0oCvl+V+5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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