SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b8796c9a328a92ff034f9698d8bca55b738e5515ad7e70decf5d6391bba7f4da' 
  AND token = 'SihMVqXySCT7bkMBImKzZ5BowXu/Wi1j9czkUQewzi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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