SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '861dffe3008862450b1fd0eb4dccaeb26430f682c211e69b97636cbd0992049c' 
  AND token = '5JTjK3ZdV/fJ+Js/Ix2RSsHGVPDyXLDKsiQvchI/95g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}