SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '702fe64fa15379184a41e39699d8ecfefc651363330aeee669998d3b6efe218e' 
  AND token = '6rfTUQRcFXBCHpnO7YLNp53ftK0jSvYIvidQeK/Zp64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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