SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45d77224e2c9b7d5ab7fba38260c5eeb7f6dcd8ebeb1afcc4e559368d89ad341' 
  AND token = 'FPyO5lGCQn1QUblwaYsrcAflBvJr70qZhbK8IHdxQ7A=' 
  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"
    }
  }
}