SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7e542fa345cd3d440ab52b6412d4d9baac0167f3f7d9b5edee869249bde9e0ac' 
  AND token = 'bDx+w2r+NfGVRLJ85DMaTOlPVoux7GznzYsuo1ycdkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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