SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b9a3121f8e92f648e067195b842271ed08442267d0d9e0d373f2907d8661c90' 
  AND token = 'l0zlLTWjMGTnMDzGAcVmpBgK4BZo8/yQTWzJSoXVGZE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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