SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '400f1ba1f6e5c2dc791608bd82ff8bb7512e4ddd1fbcfbb790427a4351bafab0' 
  AND token = 'kWbvlwiAHj/v5m5EHVp4NKohHRFul5RdYJPs3zY3Z94=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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