SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21a077a99a3b2f8e83102a97d50ec06fa8ad437671af36044b8c8af45454109d' 
  AND token = 'witA95oKQ5tZ1pmKm3wIiWone+7v38nVJNhxrzJ7rbY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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