SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '28c983bf35bbe40b19b7b37510bdc42f728e037ec8fa82db3f7b433b95af74b7' 
  AND token = 'fhqY9m4Ug3SYIlke+66wkdXpm9R6btL8tvUKjJCMp24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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