SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51f656a2f69c438f53aa5653f7f8a2e31d726cd1fab33564d19b61619aafd227' 
  AND token = 'JcKuu+kuUP/svnpnYhcdWKMe/dwCO/1+oN06ru9SfSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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