SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b49b48f9e007f194697688773879af2f06020f89a2d06fa31e495cc54349b21' 
  AND token = '1B85EQ6gKlRtJlZycWJC75Ixzcjd/EPlya0Jzusv4HY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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