SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3beff9095474a79606bc094c25da558d5c92fcefcbb1402e72876ec7f3617dad' 
  AND token = 'kpu30fAPQAe80J9KY6fp8KIVaMfe/0ZUj8KTSPDKs4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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