SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2cfb36390fb5def0b088d26fde5af4d98e459bfcd34b4431ab59765456bec008' 
  AND token = 'hAdMM+KbE4hlAXf0KFoAn0praA4+ud737eqnEmzby+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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