SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0c6303e7f3da2000d8769bda97a604b2af6dc6bf96ec4b34a0a758bc301ba8c2' 
  AND token = 'xtZU4+KHgMZyMde2giUVbxOtlmt72feAE/MucCe79EI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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