SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0d4b7331950227a33522b96b9d33a7702c09ed7e2a74a2b237605abff647c88b' 
  AND token = 'zbGp4CSzwvnF+uT3hE6OWO/jEYufRBa5xwFuRNvdnrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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