SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f0deabbd0c4e35e9811a6fd37efd6554792429bdec59a5e44ee4489c04660a3' 
  AND token = 'B49C8xupf9hhsb+19VQyA317xYsh+zjnSeEQNYFZxhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00078

JSON explain

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