SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5afb94303ac2475f2024dfa04c936de7de77ca6b4c25bf847aba7073a52aa1c3' 
  AND token = 'AelmYXepXdOOCG/ZUCdxwjzjsjMBfgUXz5Dy10d9Kuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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