SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f58b9f71d0226c784eeca650e5d54568017f5618c3b54d13dedeeb4af38e0ee' 
  AND token = 'uWDGFcB1RmJgn/BdEQmVDLs+Y9wKl4fDZb0YsFbOogY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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