SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8c2ce68efc0e20d8054b0de16a0443c5444e582965cda754756943e16148f1ae' 
  AND token = 'BhSQL2i3vUavcxK9YgFYuvRfRwNJiD8ACzM0F2jJJmM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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