SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b8c42228df25da518a7e59cf40e334880375f8b541927d6c56309f66d68a05af' 
  AND token = 'U9DoxNZHcOhW/vP5GY3zYl5FTnPbtraHW08BANy2c8M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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