SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bdf4c5dfb05042df9fccaefde814845aab52e30423dc115ad670a524f4e3a4d' 
  AND token = 'uT+N64O9Zi4ewUoWiQqGvIG1rArpz1lZKmG8qo5X8U8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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