SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8dbcdaed4800b9f63fa9b9809f3e237f15edce72b522d27269207660b5d6dbda' 
  AND token = 'ufxHgT1Z55Ggh38Y9/bFDEdR4WliNT1FVwO+0xcuihE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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