SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a36a36528225187cdbe13cef3044ad8dfe503f21c743eed58dec696332d883f9' 
  AND token = '9m5YsU9IeKEJHKxffEWeK3KRbPFXLbepWkm4Oq5e9SQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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