SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b51f3a8480a9daeac74652223d5f293a830df963fbb75be2f33899e91edabbe' 
  AND token = '+4WdxwuljTkaC6nIQUXwC2qYYzjlK1tqOGUN/T8OcUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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