SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b5a6952971d52d5b25897328a7295ef638043f7b8c065665f4e2c20ffdb2836' 
  AND token = 'TYLs4wj1GpttDohWPamdIYZq+UrBVSP7vbOpKaPeNxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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