SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f614ee09e1c4c75698fc14b8fb33c58d7eee847d33982bf07f73652f0b1e6616' 
  AND token = 'HKdWQ4xKm4qqA4CibW5D3CNSqHl9k2+zleg5l/wAePI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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