SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '893a5ab768e0a7f82dc95ad1c903bbebbcd0f6e2a13ebc7dbdcc730f387ac2bb' 
  AND token = '0udInlVjrNKlxasM6WHmYKkrnzmQbEiwsflqynHOb8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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