SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96b923a243d821c9073aecc1a8c87f6f27003e6610388519e6852be16cc612cf' 
  AND token = 'GjOAXJj9CSiKc+NH5SjibohDZy2ePk2zWYK3dT7+mj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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