SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '261328fa46cda8936760599cc36cce769fbf99e4f24d9f8e631fd7b7adbb44d0' 
  AND token = 'RYhgzc+sw3lLgl8n5cPKZqZc66Wh0UaIBrgetjdjZBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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