SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3259f8501e70ad2c8e296e9fa6f874f84700c31e77bd29dbd5a41c9506fdd4b4' 
  AND token = '1xO1WDa+HmVKazJLGvMnfuMrhTTAWOLhqPKzWjsssZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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