SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4e3cdfd9b0d03d636f987c9a3031d85de27ea89f96952a8f32552dc8f61416f1' 
  AND token = '6m7iAhnt7wk86G6mexGK75kYKb7TKy/SzuhzzA+jc9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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