SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf900febac5e979c20c231b5800966320c9b50121b0f6b32cd268841c5f21182' 
  AND token = 'hgZN5mVKelIfrjjSueHGXFa2HrWuVu1zRGNBYLU2oGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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