SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cc994ee0072a13d45f3e6a005fe3661015db98adcc350694970cdf288e4fde0' 
  AND token = 'UQAZyQGE0XvQNWAiBTZT90IR5NjvbI20Pdzj1sGh1Hk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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