SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3475aeeddc2bd6dd3a0022a806d78dd4170c9bab9f0ef27a839a96bc7c4cac95' 
  AND token = 'xcfmUzJyGV3Hv2vDNh/cl/1PuwAUk9++5PgOGKofiAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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