SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8a7f16d8cfcdda3996198a26255cd477b0a41cffe5d14599c4f4057833dc29b' 
  AND token = 'w0cdgwjFVzzTx5KDeGp6Z7MvMsvtLSYAeIgoVEdAhPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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