SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '476d5877229cbc88e3004433f7839ae558107a410cc93759d7ad2acbd992951a' 
  AND token = 'k3XttcmaBfyo4QkSQgbSyLLHoaMu1zjw9jJbd7iBXTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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