SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bc5cbe754d9a56c8bc055e58451e092a674d6335ecb347f7d6264f14f9024a61' 
  AND token = 'NLtftkYUl+bwd/PzTKKj9OwlIAhnrhGXeZmRC7hNxuI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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