SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de41e56825a551a673b1fcf8e5f48e5bafca73daf479224dbab207fbd83a7303' 
  AND token = 'Zb6vYSUcUdKWYQuWmgZE8zZWK2sKzVYWlsCyIfkh4WY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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