SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '829026fc9fc046be276f9cae6ee958389e2d7ba2a93de081ca24ba98783157f5' 
  AND token = '/PL3MmGFUWPpGdwzZrb4BJtCBrfadvURjVFbkAcIiRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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